My last period started march 9th, have not had a period since. started ovulation testing last week, for the results says that i ovulated 2 days ago. i have done multiple pregnancy test and all negative. i stopped birth control last september?

If the test for ovulation was correct, and ovulation was "two days ago", if pregnancy occurred, a "home" test won't be positive until a few days after 14 days from apparent ovulation. Given the long interval since your last menstrual event, consult your GYN physician for guidance for why a regular menstrual pattern at age "25" has not occurred.