how does labor feels when it begins

I'm not a FTM however I've never went into labor on my own and I haven't ever had contractions that wasn't drug induced. Everyone says natural labor feels different so I was curious. I'm 35 weeks 4 days. I woke up with my stomach hurting, almost like trapped gas and my hips feel like they are being torn apart. I'm not in agonizing pain or anything but uncomfortable so I got in a warm tub. It's on and off and intensifies if I bend over when it hurts. Can someone shed some light on this? Def don't want another trip to the L&D for nothing!