I've Been Tracking My Period Since I Have Married With

I've been tracking my period since I have married with my hubby ( May) , we have been having sex all the times like every day ,at first I thought my last period was 7th july to 11th July 2018 , then even before these , during the july moment I felt really sick , tired backaches , fatigue , nausea (sometimes only ), cramps , vaginal discharge is like egg white ,cravings , insomnia and constipation , but 4 times ive had the pregnancy test and it's negative , then lately in Aug 25th to 28th Aug 2018 the period came out again , what is going on my tummy is big already and I feel sth, but I don't dare to go to the doctor bcos I knew it's negative already , i'm just afraid .