I Am 30 Years Old And Have A 5 Year

I am 30 years old and have a 5 year old daughter. My husband and I are trying to have another baby I had a iud for 5 years. I had it removed in early June. I have a 31 day cycle I ovulated this month around the 6 had unprotected sex 3rd and 5th... now I am 3 days late but I am having brownish redish discharge only when I go to the bathroom not enough to even wear and panty liner... I have taken a home pregnancy test 2 days ago and it was negative... what is my body doing??