Long Distance Relationship - has she stopped loving me?

Ok, so I've been going out with this girl for 4 months now. I'm 16 and she's 15. I know, I might sound ridiculous saying this because I'm still only a kid, but I honestly thought that she was the one. I love her so much. but now I'm not sure what's happened. Let me explain.
We got together in the beginning of march, and things were so great. and they just kept getting better and better. We had our problems of course, but we'd get through them and our relationship would steadily get stronger. by the time we hit 3 months, I thought we could last forever. It was amazing, I had never felt love so powerful and I was sure that she felt the same way. But then we both had to go away for the summer holidays, so we decided that we would do long distance for that period of time. Even though i knew it would be hard, I was optomistic about it, thinking that surely it would only make our relationship stronger. We both agreed that we needed to keep in contact or we'd go insane.

Basically, before we left for the summer, I had the impression that she loved me as much as I love her and that she really wanted to be with me too. But since she's been in America, it seems very different. The first thing that made me think this was that she didn't want to talk to me much. She would never look to talk to me in her free time, and then she would just tell me she was busy. Then she straight up told me that she didn't want to come back from America because she loved it there, and that made me feel rather insignificant because that would mean i wouldn't see her again. then, when I tried talking to her once about it, she told me that she thought "keeping in contact" meant that we would just exchange a couple of small messages every once in a while just to say hi. and that's not really enough for me. I thought we were going to try and make it as much as a normal relationship as possible, which means actually spending time together and not letting the distance conquer us like that. But she doesn't want that. and then she makes comments like "I believe in 'out of sight out of mind' not 'absence makes the heart grow fonder'".. and she talks about how she keeps in contact with her other friends so much, and I'm left wondering why she doesn't want the same with me?
Everything she does makes me feel like she doesn't love me or care about me, and she never did. I've tried talking to her and letting her know about my feelings, but she just ignored me, laughs at me, or gets mad at me. It's like she doesn't care about my feelings at all. There was a whole week when she didn't say I Love You at all "because I kept complaining about not feeling loved". I don't understand that. If I'm feeling like that, shouldn't she want to prove me wrong instead of increasing that feeling?
None of this makes any sense to me, it's like everything I thought before was wrong, and it's been replaced with something that i would never call "love". It's like she'll only "love" me when everything is easy, but once things get hard, she's gone.

A few days ago, she asked me what was on my mind, and i didn't want to say, but she insisted. so I told her how I'd been feeling (for like the tenth time), and she swore she could handle it. I asked if I could be completely honest, and she said yes. So I opened up completely, just telling her how I felt. My only intention was to let her know these things so that we could help avoid them. But then, apparently I crossed some sort of line (even though she said i could be completely honest..???) and she got mad and said goodbye. she said she'd talk to me when she's ready.
It's been 3 days now, and I've had NO contact from her at all.

so yeah, that was a lot of backgrond info, I hope it made sense. if you have questions feel free to ask.

I DON'T KNOW WHAT TO DO!! I feel so lost and heartbroken, because I really just love her so much. I've never hurt so much in my life.
What do you think I should do? Do you think she loves me still?
This is really killing me...

Thanks for the help

Yeah, going to a different country can really change a person. Like, reallly change them, like their perspective on everything can be altered forever just by being there.
However, it seems that it's more the distance that has shifted your sweetheart's perspective and with her saying things like
""I believe in 'out of sight out of mind' not 'absence makes the heart grow fonder'"
it doesn't seem like you're going to get that "I love you" you want so much again. Honestly, if she's unwilling to try to work through your issues when you told her how you were feeling, then maybe she isn't really committed to this relationship.
Long distance relationships are difficult for even the strongest couples. Especially since you're young, be ready to move on.
However, if it's any consolation, I don't think that she never loved you. Young love is a really fickle thing: I think she did love you, she just didn't love you enough to keep loving you when you two were apart. Sorry, dude.