Could she be pregnant? Of the ipill?

Had protected sex with partner on 4apr. Condom did not break. Period date 20apr. (Took ipill on 16mar after unprotected sex within 6hrs of intercourse. Had withdrawal bleeding from 22mar to 27mar.) Signs of pms from 17apr. Worried if she might be pregnant History of irregular periods. Has changed her eating habits recently and sleep schedule has changed. Under a little stress because delayed periods and cannot tell her partner that. She took 3 home pregnancy tests on 25apr, 27apr and 31 apr. All negative but she still hasn't got her periods till 10may. Is it because of the ipill? I've told her not to worry cause i read they can be the reasons for her delayed periods. But i need to be sure that I'm right. *She can't really visit a doctor*. *Is this just a normal effect of the ipill? Added some more details and posting it again. Check starred sentences. Please revert.