Please help

Ok last month my period came 4 days earlier of my period date which was the 19th of july so my period last the normal 6 days. I've been getting them normal for 2 years already. But this month i was suppose to get it on 8/16 and i haven't gotten it and its been 3 days already no symptoms just a lot of back pain and bloating plus sentimental. Should i wait till the end of week to get pregnancy test or can i do it tomorrow since it bey 4th day with no period. It be are 3rd child.. i hope i am 😊😊