No, sweetheart, if you have never had sex, you are not pregnant. It is not possible to get pregnant by masturbating, (unless of course you are masturbating someone else [a male] and put some of his semen immediately into your vagina. Even then it would be pretty hard to get pregnant.) Certainly you cannot get yourself pregnant no matter how actively you masturbate.
Periods can go AWOL for other reasons than pregnancy. If you google the question ("no periods, not pregnant") you can probably find a lot of medical reasons, but here are a few I've heard of:
- body fat too low in relation to muscle (this happens to athletes and also to anorexia victims. The body won't let you get a period and possibly get pregnant if it thinks you are starving)
- stress (some women don't menstruate all the time they are at college and then their periods come back in the summer when they are home)
- hormones goofing off (you'd have to have a doctor check your hormone levels to check this)
- other body systems going wonky
Try not to worry, especially if the problem is that you haven't been eating enough. Eat a healthy diet, add some safe fats in (such as olive oil) and see if things pick up.