abnormal period

The first day of my period was very light and then the next two days have been heavy and today it has been very light again and seems to almost stop. This seems wierd to me because my periods are almost 6 or 7 days not 4?

I don’t know if this has anything to do with it but i had sex for the first time 2 weeks ago but i am on the pill and we used a condom and pull out. so there is almost no way i could be pregnant when my period was heavy for 2 days also. If anyone could help that would be great!!