Hi Jenn,
Bleeding doesn't necessarily mean you are losing your baby, but as any doctor will tell you..it's never a good thing during pregnancy and should be checked out. Even if you're not losing your baby, there are risks to YOU.
I've had friends tell me they've bled during pregnancies then ended up giving birth to a healthy baby. I myself never bled so much as a drop during my first 2 pregnancies and carried 2 healthy babies to term. Then...unfortunately, I miscarried my 3rd child 2 weeks ago, so it's fresh in my mind how it started. At what should have been 12.5 weeks into my pregnancy, I noticed a pink tinged discharge one night and went to the emergency room. When I had an ultrasound they saw the baby had stopped developing at 7.5 to 8 weeks along and there was no heartbeat. Over the next few days the bleeding went from that to small amounts of brown blood to outright red blood just like a period and I was losing "chunks" like you described. I started having cramps off and on, too. Four days after my ER visit (and the day before I was scheduled to have a D&C) I started bleeding so severely, I had to be taken to the hospital by an ambulance and ended up losing so much blood I had to have a transfusion and emergency D&C.
I hope you are able to get in to see your doctor. I'm not sure how long after a miscarriage you will still show a positive pregnancy test because I have been too heartbroken about my loss to even take a test to see, but I will tell you that I had TWO doctor appointments during the time I was unknowingly carrying a dead fetus, and they didn't catch it. I don't know if my pregnancy hormone levels had just not dropped yet, or my doctor's office just didn't CHECK them like they were supposed to. Believe me, I will have a LOT of questions at my post-D&C check-up!
Feel free to pm me if you like, and take care!
J.