Hm. Very confusing situation. Especially since you've been to more than two doctors and they aren't coming up with anything. Third time is a charm?
Now I have had a cyst in my breast that actually was infected. Painful but it didn't feel hard-- more like it was filled with fluid (which it was). They aspirated it and I took antibiotics and all was well. This sounds like a hard, painful lump. Two mammograms and they don't find this? Ugh, I'd consider one more mammogram for peace of mind as that would worry me! My hormones did cause a lump in my milk duct but it was after breastfeeding one of my kiddos.
Princess says she's had what you have had before and treated at home. I don't have this experience to share. I do think it is worth a try (although I always recommend running the regime by your doctor). If you have your hormone levels checked, ask your doctor about anything that you want to try to regulate that. They also may offer some things to help.
I did have extremely long cycles due to a slow thyroid and . . . too much estrogen. I had some other symptoms too. Mine self regulated without medical or alternative medicine intervention.
Hopefully you get tot he bottom of this! peace and let us know what happens
Yes hormones can cause cysts in the breast. I have painful cysts. I was on the depo shot and didn't have a period for a year or so. When you have your period you produce the hormone progesterone and it balances our your estrogen. Cysts are caused from high estrogen levels. I use progestelle oil and it helps. It's expensive though and I also have started massaging my breasts and has been helping a great deal so I use the oil like every two days. Get your progesterone levels checked if low then try the oil.
Is the lump painful to palpation? Is there more pain after an exam than there was before? If the lump itself is painful, you can treat it with evening primrose oil supplements.