I dunno if you have the same problems as me, but here are some ideas:
You might be getting out-rotated by the enemy. Try to use vision and wards more, and make it so that if the enemy is stronger than your team you set it up so you can at least trade objectives when the enemy takes one.
One thing you can do in the jungle is try to keep a rough idea of where the enemy jungler is on the map. If they gank a lane (or otherwise show somewhere far away on the map) and you aren't nearby, see if you can gank another lane, if no other lanes are gankable then go steal jungle camps since you know they are far away and cannot contest them with you. Counterjungling is surprisingly effective at our level of play, but only if you do it correctly. Getting caught and dying will severely screw your chances of winning a game.
Also at our level of play a lot of people have trouble closing out games. Paying attention to objective control rather thank KDA helps. Try to take objectives when the enemy is dead or across the map from you, don't waste the advantage by recalling after you win a teamfight or get baron for example. Apply pressure as much as possible while staying safe with wards. Etc.
Another thing that helps is learning tricks to optimize your playstyle. I usually go to youtube to find resources for this. There are a lot of strategy guides and other resources provided by youtubers such as Stonewall008, Gaming Curios, Midbeast, RedMercy, PhyLol, etc.
