I had a 7-8 day heavy bleed this pregnancy... Earlier on, about 3 or so weeks. Didn't know I was pregnant at the time and assumed it to be a heavy period... Had spotting again at 6 weeks. Luckily, all is ok still (now 14+ weeks).
I would definitely go and get a blood test done, then you can have another in a few days and it will give you peace of mind if your HCG levels are rising.
At least you will know one way or another.
I hope it works out for you....