How long should i wait before i get a pregnancy test?

Hey ladies! Im 8 days late for my period today. My man and i havent always been the safest with sex (until recently) and im really starting to think that i may be pregnant. I took a test at the hospital a few days ago (i had a concussion) and the results were negative. But, i cant think of any other reason id be late. There has been no change in my routine and no stress increase.

If any of you lovely ladies could possibly help me out in any way, please dont be afraid to let me know :)