Should be easier to decipher contractions!

I had my 39 week appointment today and confirmed I was feeling some contractions happening. Doc also stripped my membranes and I'm at a 2 1/2. I'm sitting on the couch now trying to time these contractions and can't always tell if I'm having one. Why isn't it easier???? Sometimes it's the baby moving around, sometimes my belly is super hard all over for about a minute and I can tell for sure. Bodies are crazy!! I wish I could tell without a doubt what's going on. I remember feeling the same way with my first labor. Anyone else?