How do yiu know its real?

So on and off for a few weeks I have been having lower back pain. Some days more intense than others, some days it is completely barely as I have a pretty high pain tolerance. When I went into labor with my first I had absolutely no idea, my water had already broken and my contractions where two minutes apart, I went to the hospital because I was bleeding... Labor with my second started at work, I didn't hurt, I just didn't feel right...and they hooked me up to monitor and contractions were 5 minutes apart, and I think I may have felt one the whole time...but now I feel this back pain, and its not consistent, it comes and goes, I'm only 33 weeks but been measuring ahead at all my appointments, so I am not 100% sure if its just part of it. I am sitting in the tub of hot water right now seeing if that will ease them, I just don't wanna call a sitter and go in if not necessary, plus I am 30 miles from hospital, so if it is labor it kinda scares the shit out of me to drive myself 30 miles while contracting...I am just at a loss for what to do right now....is this real, or is it just something I'm gonna face the next few weeks til she is here...I should note, first baby was 3 days late, second baby was 3 weeks early... Just kinda freaking out right now...