In my personal experience, and this probably goes for some others as well, you DO NOT have to shag a guy or a girl to figure out you're gay. For me it was just the realization that I never really saw myself ending up in bed with the guys I dated, and I've dated 4 guys and Master (who is female, fyi.)
At 16 I realized I wasn't all that straight. I came out as gay to my friends at 18. At 21, I came out to my Mum, I'll get into that in a second.
When I started dating Master there was this 'right'-ness to it. I can't really explain it other than it feeling 'right'. I was comfortable, there was no awkwardness.
As far as coming out, I just said, "Mum, I'm gay. I like women." No sugarcoating, just straight and to the point. My Mum was wonderful about it. I hope it goes well for you too if you eventually figure yourself out.
Yes, it is confusing at first, and sometimes frustrating as fuck, but, please, do not dwell on it. Let it progress naturally. Go with the flow. What I've observed with some people in the 'unsure' stage, is that they're so hellbent on trying to get that 'label' smacked on themselves. I've been there, and it just annoyed the shit out of me. When I just let things progress naturally, I've found the whole 'figuring out' thing easier to deal with.
Sorry for all this word vomit, hope this helps you some.