If you suspect you could be pregnant, you should take a urine test. Unprotected sex can lead to pregnancy, and each encounter increases your chances of conception. If you are pregnant, you need to start prenatal vitamins and see your doctor to start prenatal care. If you are not pregnant, and are not planning on having children right now, you should talk to your doctor about types of pregnancy prevention/birth control and what may be right for you. Having the right protection can save you from worrying each month about possible pregnancy and will allow you to make plans for when the time is right for you to have children.
A pregnancy test is always recommended. :) if you are not trying to get pregnant, use a condom. Having a baby is no joke. Take care!