Late period

Carolina
So I just started working out 3 days out of the week (which I started last week) and already my period is late. Supposedly I'm 13/14 days late, I have already taken a pregnancy test but it came out negative. 😒😔😫  - so now I'm thinking is it true that once you start working out your period starts messing up? 
-please help 
Comments -opinions are needed. Thanks. 😊