I used an ovulation kit and got a hormone surge on July 7. My husband and I had intercourse on July 5, 7, 8 and 9. My breasts are much larger than usual and I have had brown discharge for four days now. Could this be implantation bleeding? How long can implantation bleeding last? I was due for my period today July 21. I took a test yesterday which came back negative. Could it have been too early to test and I really be pregnant?

If you were due for your period today, then it is most likely your period. Implantation bleeding only occurs in approximately 1% of women. Without re-writing everything, there is a sticky at the top of this forum that discusses implantation bleeding in detail.

You can read it here

http://www.askmehelpdesk.com/womens-health/info-answers-frequently-asked-questions-our-health-expert-53865.html