When is the safest time to have sex? What r the chances of having unprotected sex during period (or day before) in shower could result in pregnancy?

Unprotected. Since many young women don't ovulate regularly the answer is don't have unprotected sex unless you're prepared to get pregnant. Doesn't matter if its in the shower, in a tub, in a car or a bed. All the above may result in a pregnancy. Probably time to use a condom and get on the birth control pill.