Hi Mike,
Well done for coming on here. That's the first thing. Stick around. Try not to get told off by the mods and if you do, try not to let it upset you (been there, done that

). There are lots and lots of great people on this forum, many of whom also run the place. So it's fab.
You're right, I think, to distinguish sexuality from gender. That's the second thing. Although they can relate, they don't necessarily. Lots of transitioned MtF's still love women for instance.
I don't know, third, if this will help but it did for me. I have sometimes worked on the basis not so much on what I want to be, but on what I cannot face remaining as. When it came to a crunch decision time I just 'knew' there was no way I could stand life any more living in male role. In fact, that's when I did tell someone I'd rather kill myself than stay a man. That pushed me to the next step because, as Heita so rightly rightly points out, there's every other option in the world available to you. Whether that means you just take some tentative tiptoes, for instance female role play, or a few more bold steps such as HRT, the main thing is that you will be starting to feed what you now recognise to be an important, and I'd say perhaps vital, part of you.
And, finally, please don't worry about your manly frame. I sat last week with someone who was an Ironman testosterone fuelled macho alpha male. She's now one of the most beautiful 60-something ladies I've ever seen. Everything is possible nowadays. Live your dream, feed your true self and remember we're always here to help. Much love and best wishes, Chen xx