I am taking Imuran. Menstruation is 3 days late, and 3 days before ovulation I made love with my husband. What is the chance that I am pregnant?

It is difficult to answer what is the chance that you are pregnant. You did not specify whether you used contraception during intercourse. Basically, the ratio 3 days before ovulation is included in the intercourse during the fertile days of the woman. Nevertheless, 3 negative tests do not indicate that you are pregnant - if I understand correctly that you performed them after or on the date of the expected menstruation, and not earlier (this significantly reduces the reliability of the result). If we assume that the tests are false negative, you can perform a laboratory test for the determination of β-hCG in the blood serum. I would also like to add that the use of Imuran requires the patient to use an effective method of contraception, because it can have a harmful effect on the fetus. I attach the leaflet to the drug Imuran: https://www.gdziepolek.pl/produkty/37526/imuran-tabletki-powlekane/ulotka/ I encourage you to watch the video about pregnancy tests: