confused if I am or am not pregnant?

So I had my last period at the end of April , tomorrow will be June 1st and still NO PERIOD. So the whole month of May I've had nothing. My boyfriend claims I've been having "cravings". I took. 3 pregnancy tests already one like 4 days before expected period another 2 days before... etc. ALL WERE NEGATIVE! We are trying to conceive. Can someone people give some advice or tell me if they have had this problem as well and what you did ? :) thank you guys