okay so, ive been on the birth control estrostep. i only took it for a month, but i stopped with about 3 pills left. i had my period for about 3 days, it was like always, except alot shorter then usual. i thought i was done because i wasnt bleeding the whole next day, but then today i started bleeding again. does anyone know why this is happening? is it normal ?

(btw- i had PROTECTED sex yesterday, the day i THOUGHT my period was done)