Regretting what I think I should've done... Help please?!

(pretext, skip if you want)
Hey there, so I'm a 15 year old guy, decent looks, plays music, blah blah blah.. I don't really like any girls at school because all the hot girls are slutty or stupid, the smart ones are ugly, and the good ones are taken (or think I'm weird). Anyways, there's this girl on my swimteam who's smart and pretty. I used to like her about four years ago, and she liked me too so we "went out". Except we were 11... so nothing really happened. She eventually just left the team for a while, and she came back about a year later, and then left again for over a year.

Last year, she comes back and I still find her attractive but she's really emotionally unstable, meaning as she would cry a lot, and we were 14 years old so this seemed kind of weird to me, which is why I didn't make any moves. She would also get really annoyed at me for just joking around with her and teasing her even though I was smiling and laughing and most people can recognize when I'm kidding easily, but she just would get pissed off randomly and then ignore me.

(recent events)
After summer, I took a 5 month break from the team and about a week after my return she was talking to her friends about how she moved up to a D cup the other day. I joked around saying I didn't believe her and stuff and she actually got kind of mad so ya.. After practice neither of our rides were showing up so we talked for about 45 minutes. We somehow ended up talking about her bra size again and she basically shows me her cleavage and her tag. Is this what a girl would do with just any guy who's flirting with her?
Also: earlier that conversation we were talking and she said she had a boyfriend but then later said she was lying, but that she was talking to a guy. Is she trying to make me jealous or what? Honestly I find her really confusing because sometimes it seems like she wants me and other times she hates me.

The very next I get to practice but It's canceled so my coach took me and the few people who were at practice headed down to a coffee shop to eat. After that, my coach and other friends basically just bailed and I was left with the girl who I mentioned earlier. I asked her what she wanted to do and she said idk so we just walked around for a while. I had a good time with her and we talked a lot even though I'm usually pretty shy (and weird). We keep walking towards a lake that's nearby and we eventually come to a dock.

I'm not gonna lie, it was super romantic. Earlier that day she was talking about how she's never kissed anyone except for in truth or dare, which she says doesn't count. She wants it to be special, and with the guy making the first move.
Back to the dock: we end up playing truth or dare. Alone. We kind of ran out of stuff to do and I was really nervous because if she doesn't think that kisses in games count, then am I supposed to kiss her or not? (btw iv'e never kissed anyone either, so it's kinda a big deal for me too).

Within the 30 minutes that we spent there, on account of my dares, she showed her cleavage and lifted her shirt. So I'm guessing she likes me? But at the same time we kind of have an awkward relationship and I didn't really know what to do... Basically, I'm and idiot for not kissing her.

After this, we're walking toward the city and she asks me if i've ever wanted to kiss her and when it was.. I said i wanted to today and asked her the same thing and she said the same. She says that she like liked me a lot last year but that she doesn't think that we'd be a good couple. I agreed. Why? I have no idea... f*ck. I'm seriously so mad at myself. She wants to kiss me but she thinks we'd be a bad couple? What the balls!?

For the rest of the day, she pretends like the whole dock scene didn't even happen. she even starts joking that some other girls are checking me out... I say she's hotter that them and she says she's better looking.. Is she not wanting me to like her? Or asking for attention? We went our separate ways and she asked if I was going to practice tomorrow and I said yes. That night I hated myself. I got about 3 hours of sleep and I got up and stayed home from the vacation I was supposed to go on so I could see her and make it right. After waiting all day for practice, I had to walk all the way to the pool and then found out that an email was sent out that practice was canceled, but I hadn't gotten it. F*ck.

So now here I am on the weekend, dreading the end of my spring break but also looking forward to seeing her again. The thing is, I had this perfect opportunity that I passed up and now I know that it'll be a really long time before another one comes up again.

An awkward thing about the team: People on my swimteam are really close, but we never hang out outside of practice. Which is why this was a golden chance. Neither of us planned the event, so it wasn't awkward. Now I have to ask her to hang out alone this time and what if she ways no? And it'll be obvious that I want to go out with her because we never just hang out outside of practice as friends. She said that she wanted to kiss me but also that she thinks we'd be a bad couple.

How bad could we be together? She likes hard rock and metal like me, which is really rare actually. And we're both pretty comfortable around each other and are into each other and we like the same things. And we both like each other and want to kiss each other so how bad could it be?! Ugh I'm so mad at myself....

HELP please. tell me what I should do; what do you think about all this? should I ask her to hang out or wait for something to just happen?