It's hard to say. Implantation bleeding is not very common, but for those who get it, it's usually light, not heavy. But of course there are always exceptions to the rule, and some women even have what seems like a normal period when pregnant. I guess your best bet is just to see how things progress in the next few days, and if you still feel that something is a bit off or have pregnancy symptoms, test again just to make sure. Good luck!
I agree with Heather. Every woman is different. I just wanted to add that if you do feel like there's a chance you could still be pg don't use tampons. It can introduce germs and bacteria to your vagina which isn't good when you're pg. Use pads. Good luck!