39 week appointment

So at 37 weeks I was .5 cm dilated, at 38 weeks 0 cm. 
Today I am 1.5 cm dilated and 25% effaced. I thought women usually stayed at 1-2 cm for weeks. Does this mean I'm pretty much guaranteed to go to 41 weeks? Thanks in advance for your thoughts. First time mom and none of my friends or husbands friends have babies yet.