10 Weeks Post C-Section...

I had my second son 10 weeks ago on October 2nd. I bled for about 3 weeks after my c-section. My husband and I started having sex about 5 weeks postpartum and when my period was due it never came. I figured it was just because my body was out of whack from having a baby so I blew it off, a week later I though oh crap what if I'm pregnant again, but we've been pulling out and using condoms occasionally until I can get on the pill due to me breastfeeding. For the last few days I've come to think that I'm probably pregnant for the simple fact that after my first c-section with my oldest son I got all of my periods on time. Well I started having some bleeding last night and when I wiped there was old blood at first so I thought thank god I'm getting my period, I woke up this morning having some cramping which is sometimes normal with my periods but this period has been so heavy I've went though almost 3 pads just today. Well around 3pm today I felt like blood was just gushing out of me so I went to the bathroom and as soon as I sat down this fell right out of me. At first I thought it was just a really large blood clot but now I'm starting to think that maybe I was pregnant and I had a miscarriage. Can I get your guys' thoughts on what you think this could be?