Do i need to go on birth control if i've only had my period 3 times from now since february of this year???

Absolutely: If you are trying to prevent pregnancy, birth control should be used regardless of how many periods you've had. It's still completely possible to get pregnant. Remember though that BC pills and most other methods don't protect against STDs, so make sure your partner wears a condom every time.

Confusing question: The answer is somewhat dependent on whether you are having regular intercourse and want to avoid pregnancy. If no exposure, no need. If you want to get pregnant, no need. Birth control is based on either preventing egg release, preventing sperm contact with the egg, or making the uterus unreceptive to a fertilized egg. If you don't know when or if you are releasing eggs, you assume you will.

You may.: Think of birth-control pills as period-control pills. If you have only had 3 normal periods from February to September, you may want to normalize your cycle. Birth control pills with harness your pituitary/uterus/ovary axis and give you a more predictable, controlled, monthly period.