Sounds like she knows you want her badly so she went for you when she broke up as a temporary back-up, but she'll leave you when she finds a "better" option. Also, she may never have sex with you. And telling her you love her so much is not going to help, girls dislike guys who are too clingy.

Sorry to be a pessimistic asshole, lol.

She probably doesn't want you to say "I love you" because after her ex cheating on her she's afraid of getting attached and then hurt again.

Then again, I'm in my first ever relationship myself, so what do I know...

If she told me I was just a back-up guy,  I think I'd cry for at least one month!  It's my first love/girlfriend!  I've never had a gf in my life because I was waiting for THIS kind of girl to show up in my life.  When we were simply friends, people asked us if we were friends since childhood because we seemed so close!

Sure it's a complex situation... By what you wrote it seems that you like her more then her likes you.

Be careful and good look!

Yeah, that's exactly how I feel sometimes... I'm gonna take it more slowly and I won't have sex until I know she really loves me.  I don't want to be broken-hearted!

If your good on the bed then BAM she'll fall for you

Happy for you but don't get too emotionally attached. Simply not sure of her intentions regarding the whole thing. It is alright be bit cynical than heart broken and gorging on ice cream later.

at 19 every girl thinks a guy is good in bed lol.  They have nothing to compare it too.

"Also she does not want other people to know we hang out with each other."

Red flag.