TTC after depo.

Ka

So I'm 23 and have been on the depo shot since I was 16. My last injection was in April 2018 and my period has not returned. I have not had a period for years but the last few weeks I have experienced serve cramping but no bleeding. My boyfriend and I decided to start trying but it feels impossible to figure out if I have even ovulated since being off birth control. I have tried ovulation tests but still nothing. Has anyone else experienced the same problem? If so how long did it take?