Worried

Okay so I had sex with my boyfriend on April 20th and we haven't ever since, but I haven't got my period this month of May and I usually get it on the 21 and it's the 29 today. So it's been a complete month since I had protected sex and I made sure the condom didn't rip or either did he cum in the condom. But I'm kinda worried I haven't got my period this month so I went to go get a pregnancy test and it came out negative but I'm still pretty worried about me missing my period this doesn't happen on a regular basis.