Hi Megan,
As others have stated, you shouldn't have any big issues with security. The scanner will detect anatomical differences and will require a pat down. They should offer you the choice of a light pat down right there or in a private room, I have always accepted it right there without a big deal. I have flown a couple of times post op and hoped to see if I made it through without incidence but each time I drew the pre check pass and did not get scanned, what are the odds? The TSA agents have seen it all and will not make a big deal of it. The suggestions about meds is probably good but I haven't followed them in years with lots of overseas travel and never had a problem....but caution may be the best bet.
One thing that I have noticed flying post hrt is that I chill easier. I like long comfy skirts and casual tops and I always carry and use a light jacket to keep from freezing during the flight.
Enjoy your travel,
Tia Anne