Depo preva shot:

Hi ladies I need some advice or examples you've gone through while on the shot for birth control. I recently started the shot but was intended to regulate my periods I had never had sex before. Recently I just got into a very loving relationship and we had sex without a condom now my period is late and honestly I am little freaked out ... So I'm really hoping I'm just paranoid could any of you tell me how effective the shot was for yall?