the TRT/muscle building study (i don't recall source) where they divided people between 50-600mg, found that hose on 50 lost muscle compared to the placebo group (natural).
50 would be below a normal natural level it seems, at that level i would aim to get of TRT and restart natural production. but if thats where you feel good, so be it. i feel great on 200-300mg. i don't care if its not natural or people call it not TRT.
if you can't go above low doses, and want to build muscle, another thing worth trying might be nandrolone to add. adding nandrolone to my TRT did not give me any mental side effects, but unfortunately have me some sexual issues (not ED, but much delayed orgasm/sensitivity)
if you got any cancerous tumor, i would look into oxidation therapies (like chlorine dioxide), DMSO, fenbendazole, and any other alternative therapies you can find and people had success with.