That looks great (especially to someone like me with zero artistic talent!), but your rivers look "wrong". Normally rivers start on high ground, and head downhill, and eventually towards the coast or a large lake - and even most large lakes will then spill off down towards the coast eventually. Rivers also tend to converge rather than split, so smaller rivers will come together into one larger river, but it's rare for a single river to split into 2 or more channels later in the flow.
Think about the direction your river flows, and why it might take that direction, allow the rivers to merge, or come together in a lake, then think about where the run-off from the lake goes etc.
Of course there are always exceptions, but if by and large you keep to common river topography then you'll find that they have a more realistic look on the map.