NuBra, availabale on Amazon for less than $40. I absolutely, wholeheartedly recommend NuBra. They are simply beautiful silicone bra inserts, most versions with a little enhanced nipple bump, and come in various sizes. I do suggest the ones without self-adhesive, because the silicone NuBra insert seems to last forever. If anyone has a problem with them falling out of her bra, she is wearing the wrong bra. I wear t-back (racer back) bras with great success. Also I love conventional sheer totally unlined bras, since they allow the enhanced nipple bump to show through. My favorite NuBra version is the size enhancer with no adhesive. They come in three sizes: S, L, XL. I have a set in each size and choose size depending on the outfit I wear.
At my place of work I am not publicly out as transgender, so under my required Polo shirt uniform shirt I wear the size small with either a racer back bra or a very sheer unlined conventional bra. Yes, people do notice them and seem to whisper about me, which I totally want. As co-worker women seem to be extremely curious about my "perkiness" under my shirt, I take the opportunity to out myself to them, one at a time. The women all seem to be supportive, by the way.
Back to the breast forms. I also like to wear a Timpa Duet lace underwire mesh bra with my NuBra insert. These also make a wonderful combination, but there is an ever so slight tendency for the NuBra to slip out of position. However, the Timpa Duet may be my favorite bra of all time. Even without the NuBra insert, the Timpa Duet on my 60+ year old man-boobs on a very slender frame gives me the appearance of A cup breasts with jiggle.
My choice of silicone insert size depends on my sweater or top or dress.
The NuBra XL is the size of choice under my ladies motorcycle jacket or when I wear my woman's wetsuit when I go surfing.
This is not an ad for NulBra. However, buy a pair. You will not be disappointed.