For some reason every month on my period my body gets very sexually excited , and i don't know why . when i am not on my period i can't . why is this?

Sexual arousal: In most women sexual excitement happens in the mid cycle around the ovulation dates. Why? Because, naturally, it is when a woman can become pregnant, so she feels more excited intercourse. Your pattern is not the most common one, but all i can say it is hormone regulated and you're designed this way. I don't see anything wrong with it. Just be yourself!