Where did you feel contractions?

Miranda • I have a gorgeous three year old girl.
I am 37 weeks and starting to question all sensations! 
Where do you actually feel contractions? In your whole stomach? At the top of the uterus? Like menstrual cramps? In your back? 
I realised I know what Braxton hicks are like - a tightening of the uterus, but not what contractions are actually like. Any descriptions would be appreciated.