birth control, withdrawal and anxiety

I'm a very anxious and nervous person. I had sex with my boyfriend (without a condom) a couple of days ago. It was a few days after my period ended. Well I am on birth control pills and I take them everyday around the same time. Haven't missed a pill and also he withdrew before he ejaculated and he said he can feel when he pre-ejaculates and he said he didn't.

so I guess my question is.
how slim are my possibilities of being pregnant?
and how can I stop being so nervous after this even though I've been through this before and had my period?

thanks.

First of all, men cannot tell when they are about to ejaculate or pre-ejaculate no matter what they say. You should not rely on someone's ideas of this when it comes to the possibility of getting pregnant.
I doubt you are pregnant. But just remember to always you a second form of birth control (e.g. a condom) even when you are on birth control and you take it at the same time everyday. If you do not what to get pregnant, it is very important to use a second form of birth control.
I wouldn't worry too much!