Regarding periods. Plz help and reply!

Hi, I need an advice, I had my period on fixed date since many years it was starting of every month then I had sex with my bf on 6th Nov for first time, we used protection but I feared so he gave me Ipill, my period came within 15 days and it was more bleeding than normal and very painful, Then next month I got periods on 17 and this month on 12.last month only the first day was little pain full rest were OK, but this month first day was very painful and there is still little pain on second day and today when I woke up pain was more now it's fine but I want to know why it's happening and when will I have normal period again and will it pain every time of my period, problem is I am in hostel so can't visit and doctor lately need help here Plz help and reply