OP, are you very skinny? I say this since being very skinny means your body isn't producing enough of the hormones for you to have a period as it would malnourish your body. And it's common for people with a low BMI or anorexia (Not saying you are, but in general) to not have periods or produce sperm, yet it may also seriously affect a person's sex drive.
Whether you are or aren't skinny, I'd still see a GP since we want you in top condition!