My advice is never ever to try to be yourself.
First, learn what kind of guys she likes and then roleplay that guy, if you don't know how to do it register on f-list as the girl who likes that kind of guys and play with some guys who will eventually teach you how to behave or at least try to read some stories or something. only then you will be good with girls.

You will not be scared if you will be playing someone else

to find out what she likes, interrogate her about what kind of movies she likes what does she think about certain events. carefully observe her reaction and how comfortable she feels when talking about something. you can even try to engineer some situations when she will face something that can reveal her interests.

If she sends mixed signals, think about her as tsundere girl and be more aggressive. You may even need to "rape" her eventually, she may somewhat pretend to resist but not really. It is likely that you already have a good relationship and only need to advance it.