First, it's great to see (er read about) all of the detail you have thought of when thinking about how you want to make your map, certainly more detail than I normally think about. Second, the tributaries are all snakey so the main river being more straight was just probably something overlooked (I do it too). Third, I agree, push the mountains apart a bit more, or lower them as you near the river. All in all though, with a couple of minor tweaks, it's ready for color. Good job and keep it up.

My 2 cents (what's the exchange rate these days for cents to euros?)