Preterm Paranoia

I went into labor with my daughter at 35w6d gestation, after having contractions for a week straight and my doctor not doing squat about it.
Now pregnant with my second daughter, due in June, everytime I get a pain or an ache or anything I'm literally PARANOID I will be going into labor. Granted this go around I have a much better OB, I'm still having anxiety that this baby will not stay in until her due date.
Just to add, my old OB found no reasoning to why I went into labor. I had contractions for 6 days straight. They were regular, but not "strong" (they sure did hurt though). On the 7th day of contractions my water spontaneously broke at 5 am, continued through contractions until 11:30pm when I had a c-section.
I'm afraid to ask, thinking the answers may freak me out more. But how many of you ladies had a preterm first birth and preterm second?