Little bleeding after sex

Hello,

I have a slight concern, I am currently on birth control pills Tarina Fe (it’s almost 10months) I have the occasion missed pill and not taking it on time usually late or sometimes early. My family is very conservative and don’t know I’m sexually active (reason for timing being inconsistent).

However, in the past 3.5 months this is the 4th time that during sex and after sex I see blood, there’s no pain feeling. First time in September twice and now December. My bf and I have sex like 2/month or 3/4 weeks, when we take it slow/pace there isn’t any blood. The sex isn’t aggressive just intense at times. The bleeding lasts for a few hours and then goes away. This time only difference was that it was pretty mucousy.

Could the birth control be the cause? Or is it just me? And has anyone gone through this. Advice please. Thank you

Btw I am 28 and have been active since 20. First time birth control pill.