To me it seems like you are really trying to stay in contact and be there for her, problem is that lot of things are out of your control-like strict parents, no phone, different states, her parents divorce, and there is no need for you to feel guilty in that situation, helpless and miserable okay, but guilty no. You could tell her this what you told WP communty, but summarize it and highlight these, your feeling in these (I am don't believe in love conquers all, I doubt you do, but still, honesty might help although it leaves us vunerable so it's a matter of trust I guess):
"as someone who overthinks a lot, i'm constantly thinking that she will find someone else. she will move on, and i won't be ready for it. maybe it's selfish in a way to admit that, i'm not sure, but it's just something that i've been thinking about a lot. her parents recently separated for personal reasons that i won't say for obvious reasons, and i feel like shit because i can't always be there for her.
she is the first person i have really connected with. i've talked to other people, but none of it sticks, and when i talk to her, i feel this sense of comfort that nobody else can give me. i won't blame her to move on because i am a shit person and such an emotional wreck, which i will admit, it probably doesn't help with the situation at all."
You could ask for her view on current situation too-feelings, what is happening now, what she thinks will happen next, how she sees you at the moment.
For communication you could use e-mails (if you can use computer at home or at school or library) or letters ( you need her adress and huh, it's risky cause your or her parents could intercept it and it costs money).
And probably the best advice I can give :"3 that you could show care in other ways then texting-maybe she would appreciate a poem, or a song recommendation, or some art you can draw and then send via texts? Or anything else you take interest in and is important to you and you'd like to share with her.
But I don't have strict parents nor is my country as big as continent so my advices might fall short. While writting this I sort of kept in mind that you are worried about her, what she thinks, so telling her that could clear up the situation.
P.S. For communication that is supervised you could use unsuspecting codes? I don't know much about those, but I am pretty sure internet could give you some ideas.
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