Multiple positive pregnancy test during heavy bleeding &

Hello, I'm 4w 6d into my second pregnancy. I've been tracking my fertility (basal readings) for two years straight. I've got a history of wacky, heavy, irregular periods (since I was 9) PLUS during my first pregnacny in 2006 I carried breech due to a heart-shaped or bi-cornate uterus which resulted in a c-section...so now that my history's out in the open, here's what happening. Three days after my first positive test, I start brownish spotting, very light only when I wipe, no biggie...then it becomes tarry and spotting on my underwear, I take another test, still positive. Now after three days spotting, I wake up Saturday morning with bright red, moderate flow, and some pencil-eraser-sized clots, decide to use my last prego test and yes, still positive! I put on a pad and go to work, changed it once...Sunday the same, but now I'm passing dime-sized clots when I wipe, go to work change my pad 3 times...and very worried. Send Hubby to the store, crack of dawn on Monday for more tests, yay, still pregnant! So now I'm regularly changing my pads 3-4 times a day, the clots are smaller and only appear a few times throughout the day when I wipe...I've had no cramps what-so-ever, my husband says to quit worrying and I'm fine. And if it helps to anyone, my cervix was low, soft, and closed since the first +test, and this morning it was midway, soft, and closed. I hope there is some one out there that can put my mind at rest, suggest anything helpful, or even share their own experience. Thank you!