My periods r irregular. i had a period dec 24 th thru 29 th then had unprotected sex on jan 12 my app said i should start on the 21 still notn neg tes?

Irregular periods: If your periods are irregular, an app cannot predict when your period is due. You did a pregnancy test that was negative, you should do another in a week. If you are trying to get pregnant, you should be taking Folic Acid which prevents birth defects, especially if taken 3 months before getting pregnant and during pregnancy. If you are not trying to get pregnant, use birth control.