Cd i be pregnant. I rule out pregnancy.

Have a 30 to 35 days cycle n regular Had sex 2 days before periods There was condom ..which did not break or tear coz aftr sex we had checkd it by water Bt it cd have come off while doing or whatever..so within n hour took i pill. Then aftr a day got my periods..3 days full n a bit on 4th... When next month came..on 13th sept..no symptoms of periods..i gt worried went to a doc..gave regestron..took for 4 days total 9 tabs..waited...today is 9th day...no periods!! Took four pregnancy tests..last one today morning..today is 14th day of my missed periods..it was negetive..what is happening idk..going nuts!! Have given blood sample for bhcg test results wd come tomorrow. If it comes negetive..can i rule out pregnancy..wen searched on internt..came to know sm ppl had negetive bhcg test bt were pregnant...plzz help plzz...