Please remember to credit your images! Just writing 'art by me' or '(c)pack number' on your post works fine. Images need to be credited whenever they're posted. :]
As for your prices, I'd say they're definitely too low! You should really be increasing them as your work is super nice. Obviously it depends on how long your art takes you, if it doesn't take you very long I can see why you'd be happy to price them lower.
I would say you'd very easily be able to sell coloured headshots for 10+ apples. Fullbodies should definitely be 20+ ! You'd be able to sell adopts and YCHs with ease too.