I really sympatize with your situation. Your story has good news and bad news. The good news is you're past that internal struggle we all seem to go through and you understand who you are. The bad news is you have some appearance issues you want to deal with. But those can be managed in at least a couple of ways.
For starters there are lots and lots of folks on this forum who began in very similar situations and they are satisfied with their lives now. Browse around old posts for wealth of information.
As for your body, we can't change our height, but you can work on loosing weight and the "athletic build". I've seen many muscular fellows transform into gorgeous ladies. If you plan to go on HRT that will help, but that's not something you go into just for aesthetics. Be sure you know where you wish to go before heading down that road.
As for clothing shopping, there are plenty of tall women in the world who manage to look fashionable, but you obviously don't have the same choices smaller ladies do. Thankfully, the Internet has come to the rescue there. I don't have that issue myself so much, but one six foot lady I know loves the jeans she gets from TopShop. Many of the big online stores have tall sections, so check them out.
As for fashion in general, I strongly suggest paying some attention to your overall style. This is what makes the difference between looking like a crossdressing streetwalker and Elle MacPherson-- style. At first glance, understanding fashion seems impossible. But I've found shortcuts and I'll share one with you.
Have you ever noticed how movie and TV stars always look spectacular (even when not on TV) while most people look like they belong on that funny site about people in Wal-Mart? It's not because they have better taste the we do. It's because they pay overall fashion specialists called "stylists" to choose all their clothes and combinations thereof. And this costs them a fortune. But we can get the same stylist advice for free. Just pick a celebrity (like Elle MacPherson) with a look you might achieve one day (or would want to) and start following them. They are in magazines and online all the time. Pay closest attention to their street clothes unless you're planning to make some red carpet galas. Doing this you'll quickly get a good fix on the right colors, clothing styles, accessories hairstyles and makeup. You may not ever be mistaken for Elle MacPhereson, but you'll probably be appreciate for your good taste rather than looked down upon.
