You've got some rivers behaving implausibly. Simplest rule of thumb: as they flow downhill rivers join but seldom split. A really clear set of guidelines is in the awesome How To Get Your Rivers In The Right Place that's stickied in the tutorial forum.
Not sure what you're saying about the island - is it simply as that upper east edge wraps around to the lower west edge, the little island is the same distance from both continents? When you're unwrapping a globe (I'll assume you have a spherical planet here :-) ) you have to use one of a hundred projections to make a flat map. All projections have some distortion- each suits some purpose better than others. So it's good to figure if you care more about the shapes of features having minimal error ( like Greenland on a Mercator map is pretty much accurately shaped, just the wrong size) or if you want east-west distances consistent, or if it represents a navigation chart where pace and and coasts matter most... So many choices. A good early decision is whether you care to depict polar regions - if they have no land for instance, maybe you don't even show them, which can simplify your view. All that to ask this: what is the map FOR ?
If you look at most world maps, they will have unwrapped the globe in a way that they wind up wider than they are tall. That is wide & tall with a typical north-up orientation... Is there a reason you have east up? Wide aspect makes sense from pole to pole is a half a circumference, where the equator is a full circumference. Basically, what you're showing doesn't 'feel' like a whole world. Which can be fine- barring interest in navigation, our Pacific could be omitted and you'd still be able to show most land masses. Another approach is to map just the KNOWN world... any shape would do. So how much do you want or need to show?
As another practical matter, the less surface you show (mnemonic: large scale = small area & vice versa) the less distortion you experience. My back yard looks about the same in any projection :-).
And welcome to the Guild! We appreciate you jumping right in with map content!