Are you fertile after 12 days of your period?

No, you are not generally considered to be fertile 12 days after the start of your period. Fertility typically begins about 10-14 days before ovulation, which occurs about 14 days before the next expected period. So if you are 12 days after the start of your period and counting from the first day of menstruation as the first day of your cycle, you are most likely still in the follicular phase of your cycle, which is the time before ovulation when the follicles mature.