Depo shot and bleeding?

I’ve been on the depo shot for about 7 months now, and I’m still experiencing bleeding after sex occasionally. It’s not been too bad for the past few times, but this time I let my boyfriend get me off before we had sex since he really wanted me to have an orgasm and I just had quite a bit of red blood come out, it was enough to shock us both and we couldn’t carry on since we needed to clean it up 😂 just wondering if anyone else has this? I’ve been tested for STIs and had my vagina and cervix checked only a month ago and there wasn’t anything they could find, I’m hoping it’s nothing to worry about, just need some reassurance 😂