Maybe pregnant?

Usually I get my period around the 20th of every month. Last month I did not receive one for October. I wasn’t too worried about it being late because I’ve had irregular periods for almost a year after stopping birth control, but I have always received one monthly. On 10/31 my fiancé and I had protected sex but the condom ended up falling off sometime during that night without us noticing. My eve tracker now says 15 days late but it really is 25 days late. I have taken 3 tests over the course of 2 weeks and all have been negative. I have had no period symptoms at all. How long should it take before we can test and know for sure?