36 week growth scan

I had my 36 week growth scan today little man is weighing 5 pounds 8 oz. He is head down so he is getting ready and boy am i ready. This is my 5th baby and i am super nervous about making it to the hospital my last baby came so quick i was 4 cm upon being admitted a hour later she was born. My doctor told me today if i was 3 cm at any of my appointments and having contractions they would admit me.. but what if im not contracting when im there? Ugh i dont know im just so nervous.