Mom’s heart buffed?

If it matters, I own all the DLC, I have yet to kill Mom’s Heart 10 times, and this was in hard mode, which I have beaten before. I was playing Azazel, I can’t remember all my upgrades, but I got up to max damage (or at least the max the pause screen shows? Which is 7?) I had a bunch of enemy debuffs on my tears, and directed tears so I didn’t have to worry about aiming or charging and releasing at the perfect moments. I used Empress right before the fight started. I was fully expecting Mom’s Heart to go down in seconds, and even if it took a little longer than expected I had six full hearts and I popped 7 One Makes You Smaller pills for maximum projectile dodgeability. I also had the mask that occasionally blocks damage. I had even beaten Mom in under 20 minutes and was on track to beat Mom’s Heart in under 30, which I know is an achievement or unlocks something or some shit. Five full minutes of the most focused gameplay of my life later, after about 300 direct, full force blasts, Mom’s Heart is still alive and I finally die. What happened? What did I do wrong? I recognize I’m not great at the game but this was just ridiculous. Does anybody know what could have caused this longevity of Mom’s Heart so I can never do it again?