I am 26 years old on birth control only one ovary i had un protected sex during my last period and have now missed my period 3 negative pregnancy test?

Likely not pregnant: Pregnancy tests are quite accurate. Since you are on birth-control and the test was negative, odds are, you aren't pregnant. There are many other causes of a missed period besides pregnancy. For example, sometimes your birth control, stress or dieting can make you miss periods. To be on the safe side, repeat the pregnancy test in about a week. Best wishes!