Am I Pregnant?

Okay loves so my period has been irregular this year. It changes every month or two. Back in January it came on the 12th for couple months then it changed to the 26th a couple months . Now For the last 3 or 4 months it’s been the 15th. Always on the 15th. I took a pregnancy test maybe a few days before the 15th and it was negative. Today’s the 17th and nothing yet. Do you guys think I might be pregnant? I keep thinking maybe it’s changing to a different date again but it’s been the 15th for awhile now.