You could easially mention it to your mom without implying you are having sex. Quite a few of my friends are on the pill that are not sexually active at all and they all have one thing in common: messed up periods! If you have quite a regular period than you might be in trouble. One of my friends period was fairly normal with exception of painful period cramps and she went on the pill to help that, as well as her acne, but that was after trying many different acne pills and none of them being successful. There are many different excuses to use the pill (even if they aren't right). Just find one.