Could this be it? What signs to look for??

With my prvious pregnancy about 6 years ago I had spontaneous contractions that put me into labor and dialated to a 7 by the time I got to the hospital from the time they started.. Currently I am 38+4 and I'm afraid I won't be able to pick up the signs. I have a high pain tolerance and often dismiss any pain to gas or BH. Right now I am experiencing some cramping, grassiness, nasausia, and some contractions. They have been lasting about 15 minutes. My husband just went to work and I don't know if I should tell him? What is a sure sign? I don't want to wait too long.