Please help!?

Jess
My last cycle was on March 16-20. I had sex but we used condoms. My period skipped the month of April and I still haven't had my period. I took like 8 tests and they all came out negative . I feel very crampy and I have gas.  I'm just rlly scared because I read online that just because you get a negative test doesn't mean for a fact ur arnt.