6 days of implantation bleeding? Help!

Is this possible, I always thought it was 2/3 days. I'm not even sure if it is implantation bleeding. It started 25/1 and then got slightly heavier (but not overly heavy) like a period over the 26th & 27th then quickly dissapeared. Now it's just present now and again when I wipe and it's really light pink. AF was due today but no sign. Also I got a BFN. Anybody had something similar to this? It's driving me mad! I just want to know either way.