What's going on? How can I get her back?

[That Guy]

I feel a good answer deserves a good question, so here's all the detail I can think of now.. hahaha
I was seeing this girl for a few months and we started of messaging each other over social media websites. We then started speaking in person, flirting etc I picked up straight away that she liked me, I had doubts, but i had a pretty good guess. I was right. I can't explain the next bit really as although I didn't fancy her, I knew she was pretty and basically I got to know her and BAM she became so beautiful
I always got told that we were "a perfect match" so I decided to ask her to the school dance. She said yes There was an after party for the dance and that's when things started. We ended up kissing at this party and spent near enough the whole night with each other. After the party we agreed to meet up at her house. At this point, I was starting to like her and I was learning more about her. Once we got to her house, we sat and talked for maybe hours.. Then we watched a film and then didn't watch the other one (if you know what I mean). We were kissing sober haha So we both confirmed to each other that it meant something. Of course talking for hours came with learnign new things. Like her ex. Although he didn't get it, all he wanted was sex. She found out and I think she really liked him so kind of sucked
For the next two weeks we texted each other every day until I ended up going round to her house again. I was getting teased about going to her house and when people found out i was goign again, they started saying i was going to have sex with her. Due to this, in mu weird head, I couldn't kiss her first when I went. I ended up play fighting with her and she kissed me first. It wasn't a long kiss and we cuddled watching the tv until it was time for me to leave. We kissed goodbye, but it wasn't as passionate as the first time. After a few days she told me I was a good kisser, which i thought was a nice comment from her.. Then it went downhill...

She started weird texts with me. She didn;t seem engaged with the conversation sometimes at all. Me being me. I panicked. I texted her at least once every day, keeping pontless conversations going.. Basically, i was being too clingy... I really really liked her at this point. There would be some days where she would text like normal again, but she still didn't go back to call me babe or anything like she used to. I also invited her out a lot of times and she always had an excuse. That made me panic more.. Every day I'd make sure I'd text her and ugh looking back i feel like an idiot, I was so scared of losing her.
After two weeks of the weird texts, i decided it was time to see what was up.. She tried to avoid it at first, but eventually she admitted that "she doesn't feel the same". She says she doesn't know why and she really wants to like me. I ended up telling her that i love her.. She said she saw a future between us and all of these things. I ended up finding out that she'd being having panic attacks and crying etc etc so I don't know if this is connected? Her very last text to me was "You're more than good enough for me"... I didn't know how to reply, so I just left it.
Nearly a week went by and i decided to text her asking how she was.. She was drunk which means she wasn't thinking of me as she always used to drunk message me.. She had to leave a party early because of this anxiety thing.

Right.. I know this question is huge, but i need the help! Honestly, I don't know if I love her, but I know that she is perfect. Well I know she's not, she just is, despite her flaws. No one has made me feel this way before or anything..

How do i get her back?
What went wrong? Is it her protecting herself? Can anxiety do this to her feelings?

I don't know what else to do nor do I know how to start up communication again... There's a party in two weeks and I know I want to talk to her and tell her I will never hurt her, but i feel there is more to say?

Thanks so much