Funny you should ask, ajtent.
I've been on HRT since May, 2017. I was very overweight when I started, and have lost most of it; I had man-boobs, and I've always suspected that what I've had since then were holdovers, at least initially. I don't know if that disqualifies them or not; I suspect any sort of boobs you can hang onto are good boobs.

When I started HRT, I specifically asked the doctor who prescribed it if I should take the E orally or sublingually; and he said orally, in a tone that brooked no disagreement. So, I did as directed for about six weeks, noticing no changes at all: physical or emotional. I decided to go with my gut and start taking it sublingually; and within 24 hours I experienced my first nipple soreness. Eventually, I got into some serious boob pain, which had me laughing at work one day. It hurt so bad, but for such a good reason.
Then, it stopped. The soreness continued; but I saw no increase in feminization for months. I switched doctors; and, on my second visit to the endocrinologist, he said my lab tests showed that my E was swinging wildly between doses -- over 400 just two hours after, then just above 70 six hours after.
You know what he did? He told me to start taking it orally again. I was stunned, because everything --
everything -- I have read says the opposite. I told him that, and he smiled. He said to give it a month, then test again.
So, that's what I've done, for about two weeks now. And, son of a gun, I think they're growing. I could still be imagining it; but in the last few days they've seemed fuller.
Weird, huh?