Coming off birth control

I have been on birth control for many years. We decided to try to get pregnant this year :) i stopped taking my birth control and had my period on July 6th. I then had a period on August 3rd and then again on September 14th (each time it was a little longer between periods). That was the last time I had my period! I have taken multiple test every couple weeks, which are all negative. Has anyone else experienced this and what was the outcome? How long did it take for you to have a normal period?