Late Period & Implantation Bleeding: What Could It Be?

Question
Hi, we're trying to get pregnant but I'd like some advice. Day 1 (first day of bleeding) of my cycle was 11 Sept, and I am 99% sure that I ovulated exactly 14 days later on 25 Sept, so we had sex on 23 and 25 Sept. I have had tender breasts & cramping & been very tired since last week, but no period when I thought I would be due on 9 Oct. I have taken 3 tests over the last few days and all negative. Then today I had a very tiny bit of light pink blood, but a normal period has not started. Could this be very late implantation bleeding? Thanks.

Answer
Implantation bleeding happens when the fertilized egg implants in the uterine lining, which would be a few days after ovulation. Therefore the bleeding you mentioned is unlikely to be implantation bleeding. It is unlikely to be periods as well, because it does not look like one. It is possible to have some minor bleeding during pregnancy, especially in the first trimester.  And secondly a pregnancy test is not going to be positive on the very day your periods are due. Wait a couple of days, and test again.