Negative pregnancy test

Janerys

Me and my boyfriend have been having unprotected sex for about a month now and he cums in me everytime! Recently i have seen some body changes.... my breast are bigger and reallly tender. And to top it off my period is 8 days late... Yesturday i took a pregnancy test at night and it came out Negative so my boyfriend said take one again in the morning, and i did and it came out negative again, how long should i wait before taking another one?