ok so a few months ago i started my period and it was still going three months later so i went to the doctor. they put me on the pill and ive been on three or 4 since then due to the fact that they either didnt work or did work and then id just start bleeding and not stop. ive been on necon 1/35 for my first month last month everything was fine. i got to the reminder pills and i had my period ...kinda..it was like two to three days at the most and it was only red like one day not heavy either but it was there. i spotted for the three or so days after. ive taken two negative pregnancy tests. could i be pregnant or is the pill just that strong to where my period is that light and short because never in my life have i had one that light or short and its kinda scary especially since im very sexually active. i use condoms everytime. someone please help im confused and starting to get scared.

ps. when i first started on these pills it took about two weeks for them to start working and an the condom did slip back one time so i was worried about something happening so i went to planned parenthood and got plan B an took it that day and the doctor had me restart my pills with a new pack a week and a half into my pack. can this be a factor in my problem? or should i still be worried?

Id really appreciate any advice i can get.
thanks.