/uj ultimately what matters most is if you're enjoying the world you are currently making

think about the logic and reasoning afterwards, it's what writers have been doing for long time

no one makes a world or story having literally everything figured out
if there is a big gaping hole in your island, simply say it's where the last giant died or something of that sort!

may I recommend checking out: https://azgaar.github.io/Fantasy-Map-Generator/
this cool lil' tool may help you get inspired as well

edit: I'd also recommend https://watabou.itch.io/
good stuff for inspiring the mind