It has a lot that I like about it. A good basis to be sure. I assume Fortune will go in the delta on the west side of the map?
My first comment would be that Deltas don't generally stick out like petals from the shore unless the water is very shallow or there has been some peculiar erosion. Deltas are the fertile depositories of silt carried down the length of a river. You may want to bring the west coast out a bit to make the delta more a gentle swell rather than an appendage.
The second comment is the river. It is possible that a river is that straight but usually they have more bends to them. Rivers are constantly undercutting their own paths and shifting as the soil is carried away. The path you describe would be possible through a large uniform body of sand or silt but it would be interrupted by rocks and land variation, perhaps even prevailing winds.
I like the map. If you're going to borrow ideas from someone here ROBA is a good choice .
I'd love to see it with some colour because that would make it much more clear.