Prepare for rejection(Finding out how she feels)

So I told my friend that I liked her and rambled a lot. We were having some issues at the time and on my part it was because of a lot of jealousy. We're still friends and close but I never got an answer on whether or not she felt the same way. I originally told her because I wanted to explain my actions and I at least wanted to keep being friends.(sometimes a ramble and I get too pushy in conversations) She said she wanted the same thing but she never told me how she felt about me.(she never been someone to talk about her feelings as much as I have been)
The problem is that we have always been clingy and flirty for the longest time(holding hands, holding each others waist, cuddling etc.) it was just a joke at first but after hanging with her for the past year I started falling for her. We stopped doing that for a while right after I talked to her, because I wanted to set boundaries. But weeks later we started at it again and now I'm in that place of getting caught up I my feelings again.(I goofed) I thought I could just live with what was said and done originally but it's driving me nuts. Not only do we get flirty but she'll start to act weird(what looks like jealousy) when I'm not giving her all of my attention and talking to other people(she wasn't bitchy but you could tell she was down). I'm just getting a lot of mixed feelings from her and its starting to bother me.

I'm going to be transferring to another school in the fall and I feel like this is my last chance to find how she honestly feels about me. I don't identify as anything(lesbian, bi, pan) All I know is that I like her and I would like to try a relationship if she feels the same. And I don't want to keep being flirty and close if the feelings aren't mutual. I keep having this fear that she'll end up being with someone else one day and thinking that it could've been me if I had the guts to ask her out properly. I already had this happen with an old friend from high school and after 8 years it still bugs me. I was literally going to talk about it today with her but my other friends show up and I chickened out of it.

How do I approach this without chickening out? I feel like I'm scared because I don't know what the answer will be? I have really low self esteem about myself and my sexuality and I don't know how to handle rejection properly. I want to know how to handle that as well because right now not knowing how she feels is driving me nuts and I've already been down this road before. But I don't have any friends to talk too and I'm not out to my family. I just feel really stuck right now and I want to move forward.