If I had sex two-three days after my period, what is tha chance of me being pregnant?

Possible. There is always the possibility to getting pregnant if not using protection. Ovulation usually occurs about 14 days after the 1st day of your period. But, this can vary, even monthly. Also, it takes a day or so for the egg to move from the ovary to the uterus & sperm can last several days in the uterus, waiting for a egg to be released. Always use protection if you do not wish to be pregnant.
Low. Menstruation eliminates an unfertilized egg from a woman's uterus, as well as the lining of the uterus (which would of accepted the fertilized egg). Ovulation occurs ~14 days after the first day of your menstrual period. The risk is low, but not 0%.