Your doctor doesn't check for dilation ? And you haven't lost your plug or anything? Sounds more like painful Braxton hicks. They can come regularly. I had some one day that were 5 minutes apart but they weren't extremely painful and I wasn't dilated or anything.
I was told if I live 15-25 minutes from the hospital to not go in until my contractions are 3-5 minutes apart lasting a minute and they're so painful I can't do anything. Or if my water breaks.