If you experience any form of abnormal period, I'd recommend a pregnancy test. A pregnancy test is the best way to tell if you are pregnant or not. Though you must wait until you miss your next period to get the most accurate results. This can be a home pregnancy test or a pregnancy test from your doctor, midwife or health department. In most cases you do not have to notify anyone of the test or the results.
If you are trying to avoid getting pregnant find a real method of birth control. Condoms, birth control pills (oral contraceptives), intrauterine device (IUD), foams, Depo provera shots, patches...there are plenty of methods to choose from. Be sure to ask your midwife, doctor or local health department for advice on the method that is best for you.