Was going to write pretty much what alexi said your situation sucks. Ive been there myself when i was 16/17. Its just parents and thier really isnt anything you can do. Its because your young and when your older it wont be a problem. As thier her foster parents they are worrying a lot more about her. Ok so they dont have reason not to trust you and you seem to be a sensible person.
My honest advice? Just ride it out. Leave things as they are, you dont want to piss her parents off by doing anything stupid this will just make the situation worse, at least your allowed to see her. If your still together in 2 years or so so this really wont be a problem. I know it seems like a long way away but it will fly by. Just enjoy the time you have together
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