I Just Had A Question As It's Been Bothering Me

I just had a question as it's been bothering me for a while I've missed my period I had unprotected sex and I took levonelle straight after but I still had unprotected sex after that again and again , I had really light bleeding but that was about it and I've done a pregnancy test 2 weeks ago and it was negative am just wonder if I could be pregnant or are my pregnancy hormones just to slow to show ? And also I've put on a lot off weight I eat allot more I eat spisific food I crave for and I've been having backaches tummy aches feeling dizzy