No period after birth control

I took the depo in January of this year we took a break from trying to have another baby my cramps and periods were getting really bad and I was afraid I may have endmetrosis. I called my doc he suggested that I do at least one round of depo to see if it would help with my cramps etc. I went back to work. I have not taking another shot since. It's April still no period. We want to have another baby before we get to much older. I am 31 and he is 32. My youngest just turned 5. Any suggestions?