I took another look at the pics you posted, and it looks like the 17 is the right size for your wrist.
I had my size 17 bracelet on my left wrist, since that is originally where I wanted it, and I noticed that the ends that stick out to protect the screws from scratching were leaving indents on my wrist. It was a tad too small. Seeing that I am going to be wearing this for a loooong time, I wondered about the long term effects of this. I didn't think it would be good.
I switched to my right wrist, and it fits PERFECT. It looks like yours fits perfect, but you never know... if you aren't sure, go try on the 16... Cartier only allows 30 days to exchange! So do it soon!