Hello I Had The Contraception Needle In The Bum That

Hello I had the contraception needle in the bum that you take every three months. I'm due for another needle in the 8th of this month but I've either missed my period this month or its late, what are the possibility of getting pregnant? I've had hot & cold flushes for the last week. Sore belly I just want to no what's going on thankyou