Hello!
I'm so sorry you're having a lot of pain. I am also pregnant and currently fighting TNBC.
My tumor was painful before and after my first treatment, but it shrunk very quickly and the pain subsided. Now I am about to have my 4th A/C treatment (the last one!!) and my tumor isn't palpable at all, and I have no pain.
Is this your first pregnancy? If so, your breasts are really tender at this point because your milk ducts, mammary glands, etc are finishing maturing in case baby is born early. I would imagine that could add significantly to the pain.
I'm no medical professional, but I found using a heating pad on my breast helped with a lot of the pain I had initially. I also take magnesium citrate, which is considered safe for pregnancy, and that can help relax muscles and take care of nerves. A bath with epsom salts is also great (epsom salts are mostly magnesium). I would ask your OB about those, but I had a lot of relief by taking the MC.
Also please feel free to PM me any time. I'm new to all this, too, and it's so crazy to do this while also trying to nurture a pregnancy.
-leah