Can I be pregnant despite negative pregnancy tests?

I had intercourse with my boyfriend on fertile days, securing myself with condoms (15-17 days of the cycle). During one of the intercourses, the condom slipped off, but before ejaculation, so what I could deal with was only a preejaculate, in addition, we figured it out quite quickly. I do not know the regularity of my cycles, unfortunately I did not attach importance to it before when I was single. Counting the 28-day cycle on August 11, I should get a period that is no longer the 6th day. I have already done 4 pregnancy tests. 2 days after the day of expected menstruation in the afternoon 3 days after the day of expected menstruation in the evening 4 days after the day of expected menstruation from the morning 6 days after the day of the expected menstruation in the afternoon The period is still missing, the stress is huge, in addition, I have been traveling a lot lately. After 4 negative tests performed after 2 weeks after intercourse, is there still a risk of pregnancy?