Well, the mechanics of a disc-shaped world are not well understood, so I couldn't say as to whether the continents could form. Since a discworld is a physically-unlikely formation, I'd say anything goes. Some items to consider, though: Is there any particular reason the continents would arrange themselves to fit so nicely in a circular area? Specifically, the bend of the main continent seems to conform nicely to the outer edge of the disc. That could be by design—the gods liked the way it looked, or it could be an artifact of whatever physical forces are acting on the continent. If it rotates around a central hub, like Pratchett's Discworld, we might indeed find that kind of arc near the edge of continents, but there might be other consequences to that kind of angular acceleration on a continent. There could be any number of things happening beneath the surface, too.
Why do none of them approach the edge very closely? Does the water at the edge fall off? What draws it downward? What replenishes the level of the ocean? A wellspring in the center? What is the reason for the environmental qualities you described: hot in the west, and dry in the north? Is there a sun and/or moon(s)? How do they move in relation to one another? How does that affect the inhabitants' perceptions of day and night? What about the seasons?
Regarding the shapes of the continents themselves, it seems to have a pretty good amount of small detail, and plenty of large detail, but it feels to me like many coasts are lacking medium-scale detail.