Hi Marcy,
Maca may do the opposite, but fenugreek will indeed help you round out, in two ways: because it increases prolactin (swelling), and the diosgenin in it increases progesterone, which grows glandular and alveolar tissue.
Diosgenin increases estrogens only very little. It's the estrogens that make the milk ducts longer, and create the banana shape. Maca increases estrogens if you take enough anti-androgens, because it increases DHEA. Testosterone is made from DHEA, and testosterone can become either dihydrotestosterone (DHT), or estrogens. Anti-androgens block 5α-reductase, the enzyme that makes DHT from testosterone.
So if you have enough anti-androgens (no breakouts), all the maca becomes estrogens. They will grow the milk ducts, and push your nipples outward. I just looove the banana shape
But if you want roundness, there is practically no limit to how much fenugreek you can use. I went up to 10,000 mg and still grew, at least temporarily, from the swelling. If you are afraid the progesterone will stop your permanent growth, you can add goat's rue for more prolactin (swelling) without progesterone.
Because fenugreek does not increase testosterone, and it increases estrogens only very little, you can't stall on it. The anterior pituitary gland measures the total amount of sex steroids, and if that's too high, it shuts down the production of Luteinizing Hormone (LH), to stop the ovaries making more estrogens. Fenugreek can never get you in that situation.