Eek! had a weird cycle..?

My hubby and I have been TTC since March, and though we didn't have a BFP (believe I tested too early) I had all the symptoms, including missed period. I had to reschedule my dr's appt, but started spotting on 8/29. It was very light and dark brown in color. Over the next 4 days, I ped 3-4 blood clots. I had a very light cycle, which is REALLY abnormal (usually my cycles are around 10 days with heavy bleeding and lots of cramping/clotting) however I only seemed to bleed heavily after I ped a clot. But I didn't have pain/cramps.. just a weird pressure down there. I was on Depo for 4 yrs, and got off of it over a year ago. So I'm not sure if it's normal to still be ping these clots. My doctor said I shouldn't be, nor should my cycle be this long but they can't find anything wrong with me thru blood work (at least a couple of months ago when they tested) Any suggestions? thanks!