Increase atlas size to 4096. [Lighting tab >> General GI >> Atlas size]

Tested with your settings:

[![enter image description here][1]][1]

Increase **bounce intensity** of light. Also increase **indirect intensity** and **bounce boost** under General GI in Lighting tab. These should be satisfactory. If not put some bake only point lights where shading is not working good. Then bake.

 [1]: https://i.sstatic.net/eW390.png