I'm having problem regarding my delay in periods. 30-40 days lasts only for 3 days. And I'm a virgin.Had my last periods on 11th March. Then on 26th march i had sex with my bf, but i was wearing clothe below ( salwar or you can say pyjama) while my bf was on his underwear but sometimes naked ( hadn't put on condom) .My bf is sure he didn't cum or pre-cum etc on me but he did on his underwear .but i'm still tensed about it.

Again on 29th March we had sex, but this time I was naked while my bf was wearing his underwear , later he ejaculated few drops of semen on my bikini line , which i quickly washed and consumed ipill 72 within an hour.. On a big note - my bf didn't penetrate niether on 26th nor on 29th , but he did fingering up to 1.5cm , does this breaks hymen,? as I'm virgin. Then after 7 days on 6th April , I had brown discharge and lil blood for 2 days . And before, on  4th April i did an ultrasound test which showed polycystic patterns. .

Today is 18th April I did pregnancy test at home with a kit , it showed negative , but I'm still tensed am I pregnant or not ? When do I'll get my periods? Please help. It's been 2 weeks after sex , I gavehav felt any pregnancy symptoms but yes had lil stomach pain and lower back pain ,may be it's because of my busy schedule or is it a  symptom ? . 

Please reply .