Not sure what to think?

My husband and I BD'd right before my ovulation week then he had to leave for work for 6wks. I got my period while he was gone but I am about 5 days late. I tested two days ago and it said negative. I don't know what's going on. Usually my cycle is around 30-34 days and now it's been 40. We have been TTC since December and I have no kids so I don't know what this could mean. Please help!! Thanks ladies!!