I am extremely worried

Hi,so i my period is 5 days late.I took 3 tests-on the 1st,2nd and 4th day of the delay.They were all negative.I will test again on the 8th day.I’ve only had sex with a condom from the beginning till the end and my bf cums inside me.After that i fill them with water to check,there were no leaks.However,i am worried.Please tell me if there is a reason.