If you've come to just get this off your chest: Dude, I get you. It always sucks when you feel like like your art is going nowhere, or even backwards. I've felt that before myself, and I hated it. Art is a skill just like any other. Sometimes, you'll feel like you're imporving in leaps and bounds. And sometimes trying to improve is going to feel like you're trying to dig through a mountain with a tiny plastic spoon. That's totally normal, and I promise it's okay to be frustrated by that! It's important to me that you know that last bit. Just because something is normal doesn't mean you have to be fine with it. This ain't gonna last forever. So long as you don't give up entirely, you'll see improvement again eventually! I hope you're able to keep a love drawing in spite of your frustration.
Also, your style is going to change over time. I myself used to have a way more complicated style, which I thought made my art better. In some ways it did, but drawing every individual scale on a dragon isn't inherently better than not doing so, and vice versa. It works for some styles, but not for others. Plus, you'll find that different aspects of your art improve at different times. Sometimes, you'll get better at the technical aspect of it: the anatomy, the color theory, the poses. Sometimes it's your character art that improves. Sometimes it's your backgrounds. Sometimes, you'll look back at old art and realize you've come further than you thought when it comes to character design. Sometimes, you improve greatly with eyes specifically for some reason. And sometimes you still can't draw that realistic hand, but you can put a blob on the end of an arm and call it one! There's honestly so much to art, and you're not going to improve in every aspect at once.
If you want some advice: There are plenty of things you can try that might help! They won't fix everything immediately, but they can help when you're stuck in some way. I've found that making silly little doodles helps me greatly when I lose motivation to keep drawing. (Which, I am aware that you do, in fact, still have motivation. Even so, it's a fun little thing to keep for a rainy day :3) I like to doodle little vines, flowers, and stars. On occasion, I'll devote a page in my sketchbook to tiny nonsensical doodles. One fun exercise is to make a weird scribble on a page and try to find a picture in it. I love these because while the things I find are still recognizable, they end up cartoonish and imperfect. They just make me smile and help with creativity!
Another helpful tip is to study what you want to draw. Look up both photos and drawings. See how, say, a cat actually looks, then see how others have drawn them. Practice breaking down real objects into basic shapes. Every object can be broken down into simple shapes connected to each other. Look at how long limbs are in proportion to the actual body.
Also, you ask for conructive criticism a lot, which is a good thing! When you do that, you get yourself another pair of eyes (or a few more) that can help point things out. When you spend a lot of time on a drawing--especially uninterrupted--you may become blind to some things that aren't quite right, or you may end up fixating on one specific thing that just looks "off." A fresh pair of eyes, either your own after a break or someone else's, won't have that same issue. That thing that looked "off" to you may look amazing to someone else, or they may be able to point out what's wrong and why and maybe even a way to fix it. Something you might never have noticed may come to light. And other people can offer valuable insight and tips you may have never thought of before.
(Don't overdo it with asking for criticism though. Since there's always, always going to be room for improvement, it may get a bit discouraging to keep hearing "well this could be better." or "this looks a little funky, but this could help." Even through every drawing is an opportunity to improve, it's good to sometimes create something simply to create something. You can draw simply to relish in the fact that you are able to, that you can call something yours because you made it yourself and it has never been anyone else's. It isn't always about trying to make your next masterpiece.)
Above all else though, take breaks from drawing. They can be as short as a meal or as long as... well... however long it needs to be! If the thought of drawing stops seeming enjoyable, it isn't a good idea to keep forcing yourself to do it. If you keep forcing yourself to do something out of a desire to get better at it or obligation, you're going to learn to resent it before you grow in your skill. (a desire to get better is a good thing, just don't let it be the only reason you try.) I'm not saying to shirk your art responsibilities like commissions, especially if you've got close deadlines. I'm saying maybe stop accepting them for a time, or pause artfight. (if artfight is fun and something you really look forward to, keep doing it. If it's more "well I'm signed up and I already started these attacks and look at all of these attacks I've gotten that I should retaliate." then take a break from it.) Plus, taking breaks gives you those fresh eyes I mentioned earlier. There have been times I've tried something new with drawing legs, I stepped away for a bit, and came back only to realize "hey wait, legs don't actually bend that way." Plus, if you're burnt out, it's the best option to take a break. You don't fix a sprained ankle by continuing to run, and you don't fix burnout by making yourself sit down and draw. Sometimes you need a prolonged rest, and that's absolutely okay!
Tutorials can be a huge help too, if you can find the right ones! How to draw books can help, though I don't reccommend any of those super thin, 10-page-long ones. Those have a tendancy to assume you don't actually need a how-to-draw book! They don't go over any basics or techniques and just dive in to "okay draw these circles that represent the body. Okay now the limbs. Now draw the details. Now color. Behold your lovely owl!" and leave you thinking "Okay but how do I do that? How am I supposed to know where exactly this attaches to the body? How do I get from point a to b?" The kind of how-to-draw book that works best for me are much thicker. They spend time going over the individual parts of, say, a bird. They'll show you how the head should connect to the body, how the wing extends, how the beak moves, and how the claws grasp braches. Then, they'll go over how all of that fits together. I personally love them. I'll see if I can find any reccommendations, if you'd like. Of course, there's also online tutorials, obviously. Just like with books, not all channels/videos are going to be helpful. Sometimes they're meant more for enjoyment or a show of skill than for helping someone learn. Again, I'll see if I can find any reccommendations.
I hope all this is helpful! And I hope you're able to feel better about your art! I for one love your style and hope to see it improve the way you want it to. If you ever need tips or anything, just let me know! I'm happy to help wherever I can. :3 I wish you the best in your artistic endeavors! (also, sorry for the wall of text XD Maximum art genie right here lol)
Remember, done is better than perfect. You can always go back and spruce something up later. And something done simply for the joy it brings is amazing, regardless of skill.
Spring Month: 1 
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Fog Moon: 
