I sympathize. I have been looking for almost the same thing as you for a long time. The only difference is that I need something that is a little wider as I often travel with multiple music scores and a couple of textbooks. It is amazing to me that more companies don't make a briefcase with a water bottle holder.

Here is one that I am considering. However, it is really expensive compared to others so either it is amazing quality or just overpriced:

http://www.guragear.com/chobe-19-24l-bag-only/

It has everything you ask for except it is not really slim. It also expands if you do have more stuff.