Help please!

So Im on the pill and something weird sometimes happens. Like I get my “period” one week before I should get it. For example, i just go my period today, but I still have one week left of pills to take.

This is not the first time it happens. Usually when it happens I have my period for like 2 weeks and that is really annoying. I missed on day of my pill the first week and I took the pill late twice on the second week.

Does anyone know why this happens or how I can prevent it ?