Depo? Preg?

Is it a possibility I’m pregnant? I been on the depo shot for a year now and June was my last injection.. I had just gotten back with my kids father in Sept and been very sexual. I haven’t had my period since my first of depo and I haven’t had my period since I have not gotten my shot.. but I’m worried I could be pregnant.. is it a possibility? We have 2 kids together and I don’t want a 3rd just yet until we’re both stable and I have his last name.