To me it seems like you have the sexual side of things sorted but judging by the day after you don't have the comfort or rapport or call it what you will.

There is something there, she slept with you twice so I don't think you need to bother with IOI's it's on already! You know this!

You need to work on the other stuff, go there have a good time talk to lots of people, don't worry about what she thinks of you because this will stop you being fun, you will be too busy analysing things to be a carefree spontaneous guy. Speak your mind, be confident and high energy then she'll be attracted to this, don't forget the sexual intent though but you seemed to nail that (quite literally) before.