2 days after my period ended i took a shower and my boyfriend masturbated and ejaculated on my butt. im worried semen could have traveled in the water and gone into my vagina. please help?

Conception is less likely happening by 2 reasons: first, semen with live sperms could not get into the vagina from your butt in standing position and second, ovulation less likely happens right then or within next 3 days if you have a regular cycle of 28-30 days. Take care.

Sperms have to enter inside the vagina to be able to impregnate. So unless the ejaculate was on a finger which was pushed inside- the chances are nil

Pregnancy is not possible in above circumstances, if vaginal intercourse did not take place. Contraception remains otherwise key in avoiding undesired pregnancy and associated anxiety, specifically when intercourse becomes possible.