About game design itself, being a programmer and not a game designer myself, I actually don't really know what advice I could give you haha. I suppose that game designers should play lots of different games, but this is also the case for others game profressions since it's a very generic advice.
Otherwise it seems you're already working on some games and doing game jams, which is great and you should definitely keep it going, personal projects are really what will make you get better and it's also a proof of motivation :)