I was a similar height and weight to you and had a 40 inch chest, 17.5" biceps and a six pack with a body fat% just over 10. In the almost 5 months I've been on hormones my biceps are down to 13.5" (yet they still look muscular), my chest across the pecs is 39" and the six pack is long since gone. Now to be fair, I've stopped lifting all together to try to get these exact results. With that low body fat, I didn't like all the vascularity and muscle definition, it looked anything but feminine. I've maintained cardio fitness and have lost quite a bit of weight (probably due in large part to the loss of muscle). My plan was at 6 months to start a high rep, low weight strength training regimen just to keep my muscles in shape but to hopefully allow the continued reduction in overall muscle mass and definition. I'll be posting a before and after collage in that thread on this forum, so take a look if you're curious.
I would think that if you keep up a solid routine of heavy lifting you'll be able to keep a fair amount of the muscle. What you probably do have to decide is how much you want to keep. Personally, I agree with the attractiveness of a physically fit woman, but too much muscle mass and definition on a woman I think is actually unattractive. Your views may be different. Good luck.
