I'll reiterate what Sweetpea said, the "pull out method" IS NOT birth control and you can and eventually will end up pregnant. Pre-ejaculate is ALWAYS present. It's the clear fluid that the penis secretes during arousal. This fluid DOES contain sperm. Not as much as ejaculate but it only takes 1 sperm to get pregnant. Again, as Sweetpea said, he doesn't feel when the pre-ejaculation is released.
If your period is not like a normal period, yes, you can be pregnant. Some women get implantation bleeding. Which typically occurs around the time the woman is supposed to get her period and can be mistaken for a lighter period. It's normally just spotting, no more than a teaspoon full, but it is possible for it to be a slight flow.
Wait two weeks from the last time you had sex and take an hpt.
First and foremost, the "pull out method" is not a form of birth control and can easily get you pregnant. Any time a guy has an erection there is something called pre-ejaculation that is always present, he doesn't feel when it happens, and it has been known to contain sperm. You are playing with fire when you have unprotected sex and don't want to get pregnant. There is no safe time to have unprotected sex.
If you are having a "period" that is different than normal, take a home pregnancy test just to make sure. Sometimes women can have bleeding that occurs during pregnancy for a number of different reasons, so it is possible that this is what is going on. Take the home pregnancy test tomorrow morning, using first morning urine and then go from there. Also, if you have not been tested for STDs, then you may want to do so.
Hope it all goes well.