It might pay off to put the landmasses in perspective too, but it might not. It looks pretty good to me.
Abu Lafia has some amazing land form works which you may be able to draw technique from, such as
this one. And of course there are quite a few others but I can't recall specific examples ATM.
I am curious about the canal that is cut through the southern continent. What sort of thing could justify the expense and effort of building a canal when there doesn't seem to be any real advantage to having it? You could just sail up either side of the that island, and since you have a sea passage in the middle there... There were ancient canals or
at least plans for them that were made, but they always had dramatic time saving effects, as do our modern ones (the Panama and Suez canals, which are in competition with one another, and save the trip around gigantic continents). Alternatively canals provide passage to places boats could not ordinarily get to (the St, Lawrence Seaway).