Spotting during intercourse.

So my husband and I are trying to conceive. For the the last 8 months my period has been like clockwork. Like literally I could tell you in advance the day it would start on and it was always correct. Anyways, my cycle should have started today. (They are consistently heavy for 4 days). Last night, after intercourse we notice bleeding and we just assumed it was my cycle but today...NOTHING. No bleeding, no cramps, nothing. I have been getting negative PRego test results (typical since I always got a negative result even when prego with my 9 year old daughter)