Didn't know for sure; I couldn't know for sure, really. I'd like to say that, in my gut, it just felt right; in a way it did if I thought back to childhood and my first reactions to a female puberty, but I still had nerves... I was still listening to all the people who said that I could enjoy being female, that I was *meant* to be female--all I had to do was give it a chance, get laid (use the hole), show off my body (in their opinion, a very cute curvy body), put a smile on that face (cute, feminine baby-face). Okay, so I'm seething at the memories of their words.
I gave it a shot, kinda. Not really. I put off transitioning for a year, at least. I was already dressing as femininely as I could tolerate; no way was I trying random sex as a female just to convince myself I was one; smiling was becoming harder and harder. I just decided to take the leap because after the panic attacks, convulsions, and dreaming my own death every night for several months straight, I figured it really couldn't get any worse. As it turns out, even if transitioning can be awkward and stressful at times, it just doesn't compare to the stress of forcing myself into a female role. The suicidal impulses are gone; the urge to hurt my body is gone (hell, I'm even able to refer to it as *my* body); I think that counts for something.
As for not really knowing what it's like to be treated as male in society, I feel ya. I'm still not 100% sure what people gender me as. I think more than anything, they just treat me like I'm very young. It's awkward; I sort of feel like I am a teenager because that's how I'm perceived. I guess my problem is more that I have no idea what it is like to be treated as an adult in society; I have never physically (even when perceived as female) been taken to be more than 18. Once people get to know me they catch on to my true age, but just out in public... I've always been a kid or a teenager, never an adult. There's a certain uneasiness that comes with never being perceived correctly and it leads to the question: what will it be like once I am? I expect it will feel just fine (like coming home, as someone said), though it will take a little getting used to.