The art of coming out, to your significantly older crush

I want to tell her that I am also interested in women. Specifically, said woman of interest currently, being her. I want to do this because, although I thought I made it obvious, she still thinks I am straight. I know she is bisexual as she has talked with me about it several times. There is a strange chemistry between us that I don't understand. Sometimes it's flirty, sometimes it's very cold.

She is 15+years older than me and I also don't have many friends her age to compare notes with. I'm 25 and new to all of this. I do know how my extremely "friendly" straight best gal friend acts with me, and even her actions aren't to the level that me and this crush interact. Perhaps im more perplexed given the age gap but we are moving quickly, where you sweetheart cuddle, slap each others butts, help them change their clothes when the are injured, hold hands, touch each others arms. Etc. Etc. And then get awkward has heck about it the next day.

Anyways, I feel like she is attracted to me but at the same time is holding her own and not giving into it. I want to tell her that I want to date a woman next (namely her) as I'm just admitting to myself that I also like women. I also want to make sure I keep her friendship should she not be interested in me.

So how do I do this? Are there any key words I can use to see if she does like me? Or do I just say it casually that although I haven't, I want to explore my sexuality because I've always been attracted to women.

Advice appreciated!!