Pregnancy Risk After Unprotected Sex During Period: Seeking Information

Question
My grilfriend(age 20) and I(age 25) were infact incredably stupid! i penetrated her on the 5th day of her period without a condom.  and now we are worried that she may be pregnant? I never ejaculated and was only in her for a miute or two. if anything came out it would have been precum. i know that it can contain sperm and that is why we are worried about it. i ejaculated the day before we were together. could my precum have still had sperm in it? or is sperm always in precum? i know that this was incredibly stupid on our part and we are both kicking ourselves at the moment. please get back to us asap thank you so much!  

Answer
If she has a normal 28 day cycle (from the first day of her period until the first day of her next period) ovulation occurs on cycle day #14. She can ONLY become pregnant if you have sex on cycle day #13, 14, 15, or 16. She cannot become pregnant if you have sex on the fifth day of her period with or withodt a condom. However, if she does not get her period ont time, wait an additional week and take a prgnancy test to be sure. You produce sperm every day and there usually are around 300,000 sperm in the "pre-cum" which can cause pregnancy if any of them get into the vagina. If you try to withdraw prior to ejaculation, these sperm can be "milked" out into the vagina by reflex action and she can become pregnant if it was at the correct time of the cycle (cycle day #13,14,15, or 16.). Don't worry.