8 weeks 6 days and still spotting

I'm 8 weeks 6 days today and I have been spotting since December 3rd. It started out dark red when I wiped and tapered off to brown a couple days later. All my friends were sure it was a miscarriage but it turned out to be implantation bleeding. But it's always there, every time I wipe or it's in my panties. I have an ultrasound scheduled for this Thursday where I'll be 9 weeks 5 days but I'm so scared this is a miscarriage. I have had 2 miscarriages in the past. Anyone with insight or comforting thoughts would be greatly appreciated. Has this happened to anyone else and it turn out ok??