CM/Negative test


So I've been having really sore nipples for the last week and I am currently 4 days late for my period. I've taken 3 tests and they are all negative.. I am never late for my period and my cycle is always 28 days. I have just been to the toilet and when I wiped this was my CM can this mean I'm pregnant or not.. please help... I did have a miscarriage in September 2017.