Birth Control And Irregular Bleeding

The bleeding could be from your cervix, it could be from slight tearing. There's no way for us to know for sure.

It's not likely that it's from the pill, since you say it is only when you have sex, although it is normal to have some spotting in the first few months of taking the pill.

The bleeding could be because he's hitting your cervix and it is already irritated/sore for some other reason.

You should see your doctor/gynecologist and they can check it out to see if they can find the cause. It is not normal to bleed every time you have sex. Many women never bleed during sex - including the first time.