I'm 18 months HRT. I lost 3 pounds during my first 6 months HRT, and another 5 pounds when I had bronchitis - probably this was because I was eating extremely light. Since then I fluctuate +/- 3 pounds, but my weight stays pretty stable according to the scales. However, people who haven't seen me in a long time say that I have definitely lost a lot of weight. Perhaps I lost some muscle weight, and maybe fat redistributed itself in a way that I appear thinner than I really am.
Fwiw. It seems that a lot of MTFs gain weight from estrogen because estrogen slows our metabolisms, making it more difficult to lose weight. A lot of FTM's also gain weight - that is caused by the increase in appetite from testosterone.