Hi Redstar - and welcome to the Guild!

The colours work fine for me (it's a tried and tested colour combination) - did you make the map with CC3? I really do like the way you've depicted the buildings - it works well to the perceived scale of the drawing. It's a really convincing map. Presumably there are more buildings to come?

If shallow waters are to be an important part of the map, you could contours, but I'd suggest not having them outlined in black and maybe feathering them a bit.