In which days after my period there are few chances of pregnancy when he cum inside vagina. Cycle 28 days. Not afraid about STD.

No guarantee. Pregnancy has been reported for any day of a woman's cycle including during menses. It is more likely during the week surrounding the halfway point, but there is still a risk on any day. If you want to avoid pregnancy, use some form of contraception every time. Condoms are cheep and effective if used correctly.The timing and "pull out " methods are incredibly poor methods.