water broke?

( TMI) i need to know how you knew if your water broke. i am 17 a ftm and i think mine may have just now. i was pleasuring myself and i sat up was not done and a gush of liquid came out. i cant smell anything its on the bed. im going to monitor it for an hour and see if it soaks through my underwear. i already peed. im 35 weeks already almost 2 cm dialted and have a foward cervix thats 20% effaced. i have had constant contractions since 32 weeks. i need to know if this is a reason to drive 45 min to the hospital or not.