Still a chance?

My husband snd I tried a few times in February and I’ve gotten negative tests all week, but if I look at my calendar it says the highest day we tried will be two weeks on Saturday.....do u think there is still a chance? My period is supposed to. One on Saturday? Also, we have been trying for 6 months....with my other 2 we got pregnant right away....my period always comes when the app says it will do does that mean I can trust the ovulation day is correct?