Trying to conceive

I went off the pill the beginning of November.  I had a period the week after which was expected.  I have not had one since then, BUT I ovulated Dec 20th (I am sure because I took an ovulation test clear blue digital).  My husband and I had BD the day before and day of ovulation.  I have not had a period since but pregnancy tests are negative.  I am very confused.  I would say it's just taking time after getting off birth control for my body to go back to normal except for the fact that I ovulated.  Don't they go together?  What is going on?