Depo shot first period questions

Adrii

So I got my first Depo shot August 5 but the day before I didn’t have unprotected sex, but he did rub his penis on my vagina and came on my vagina i’m not sure if Any got in or not. I don’t think so but now I’m late on my period but I know it could be a side effect from the birth control. Just wanted to see everyone’s opinions.