I was diagnosed with GM last year and only just recently found out I'm pregnant. I was on prednisone for about 4 months but stopped about a month before I discovered I was pregnant. My doctor has also discouraged me on continuing any antibiotic for the inflammations I was having. So now I'm drug free.
As for the symptoms, the inflammations did go a bit worse at the beginning, but now it has been 3 weeks since I had one, so I guess that's an improvement. The lump size has grown though, I think it might be because the breast itself is growing because of the pregnancy.
To be fair, most doctors I've met did discourage me from getting pregnant (I told them I want to stop the steroid because I want to try to get pregnant) while having GM because it is feared that lactating will make it worse. But I'm already pregnant now,so I'll just wait and see how it'll be.
I don't know about getting pregnant but I do know with the medication I take , methotrexate, you can not get pregnant while on it because its a class x drug and would cause serious birth defects or miscarriage. My doc wont even prescribe it unless u are on birth control or have an iud. So talk to your doc about options.