How long have you been using the bio-identical hormone cream? It takes a while for your body to adjust, so give it some more time and also follow a skincare routine that works for you. I have problems with my ovaries (PCOS), but can't relate to what you've been through. I do struggle with melasma though - some sources say that it can fade once your hormones readjust (esp. once your estrogen & progesterone levels become more balanced), while other sources say that once you get it it's hard to completely remove it. I have, however, managed to fade mine so I'll give you some tips that worked for me.
1. Wear sunscreen, which I assume you are already doing. I use a primer with SPF 30, and I also apply a vitamin C cream on top of that.
2. Every night I apply grapeseed seed oil on the areas with melasma for 1-2 hours, then wash it off. I use the organic kind, the same I use for cooking. It has a very high % of vitamin E and I found that it helps break up the dark pigment if you use it consistently.
3. After washing my face at night, I apply a kojic acid serum. It basically helps lighten the pigment.
4. Sometimes I apply a yogurt mask to the melasma to help it fade faster.
As for makeup, I tried yellow-based concealers (Physician's Formula makes a liquid concealer with yellow and regular color) and peach-based ones, but I can't cover it up completely. Using blush after you apply your makeup helps distract from it.
I hope this helps. Good luck!
Supplements: inositol, DIM, digestive enzymes [don't need them every day anymore, only on cheat days], herpanacine & vitamin C with rose hips [not every day], regular sun exposure for vitamin D3.
Lifestyle & Skin Care: Low histamine diet, avoiding unnecessary stress, balancing skin's PH (using Image Ormedics), using distilled/ filtered water to wash face, occasional high frequency facials... (although I have been slacking lately)
** Find the cause, find the cure **