Hi! I was in the same exact boat as you! The SA was encouraging me to get an 18 versus size 17. The 18 had lots of movement which I was told was the way it should fit. However, I personally don’t like a lot of movement, so I went with a 17 and so happy I did!
I think it’s personal preference on how much movement you want!
This is really helpful! Does your 17 fits similar to how the 16 looks on me?