Depo Shot

Hello! My SO and I recently had sex without a condom and he came inside me for the first time. It's week 7 on the depo shot and it's the only time we've had sex without a condom and with him finishing inside of me. At first I wasn't all too worried until I saw a post on the internet about how the depo doesn't really work which kind of freaked me out. Right now I'm not really sure if I should just forget about it until my next shot (I have my next shot on 20th of December) or start kind of worrying about it  now???????? 😅