Help.

Hi, i'm now 20 days late. My next period is due in a week. I have had 3 negative tests and i'm not sure what to do. I had a brown discharge about 2 weeks ago now it lasted a day. I have had really sore hard nipples for the past 5 days.. so sore that when my top brushed past it or my bra rubbed it really hurt. The last test i took was a week ago. I'm normally on time and lasts 5 days. My doctor is no help and i'm not quite sure what to do. test again or wait a week to see if my period shows.. any help will be amazing. Thank u x