Painless contractions for over 12 hrs

I had painless contractions for over 12 hrs! They were coming at one point from 7pm-10pm every 3 minutes and I was just waiting for them to turn into the real thing. I was finally able to convince myself to go to sleep around 4am and I woke up around 9 and had only had a few since then. Still not too painful but harder to breathe when they happen.. Anyone else experience this and had it actually turn into labor? I called my doc and she said to go in if they become painful but she also said they could very well just go away too!