I'm 18. my question is when can i expect my sex need to get lower? when will i gain more of a control over my desires?.?

Sexual desire...: ...is highly variable from one person to the next. It often declines beyond the teens or twenties, but usually not much until later in life. The important thing is to be responsible in your sexuality: wise partner selection, contraception, STD prevention (condoms, safe sex), periodic STD/HIV checkups if non-monogamous. If this seems a serious problem for you, get professional counseling.