Period 8 days late negative pregnancy test

So I was due to start my period last week and nothing has happened so I did a test this morning which came back negative. I’ve had no other early pregnancy symptoms and no pms symptoms either. I have been going to the gym recently probably around twice a week other than last week. Could it be the sessions at the gym that my body isn’t used to that has caused a delay? If so how much longer will it be before it starts? According to the app I ovulated about 3 weeks ago?