need some advice please

My bf and I have been TTC for about four months. I thought AF showed up on Friday last week after being over a week late. However after heavy bleeding on day 2 i only spotted afterwards and nothing after yesterday morning. Three PT have been BFN (week before "AF" started) I have a Bicornuate uterus with uterine tilt so I typically will have longer than normal bleeding. Any advice would be appreciated not sure if this could have been implantation bleeding? Any one familiar with this or have any advice?