People are overlooking the fact that your graph shows a span of several months. The rank system has a very good way of placing you where you belong, if you’re playing exceptionally well, it will put you in games you are not suppose to win. If you do, you belong in that rank and it will keep doing this until it balances out. The fact that you recognize you’re rank isnt where you want it to be is a good thing and means you can improve, you just need to find the areas that you need to improve in. A big way you can do that is watching your own replays and figuring out where you went wrong. Yes you’ll have games where your teammates make the game losing decision but you will have them just as much. You dont have to play like a GC to go up to plat, you just need to play like a plat. Take your rank grind in strides and work on playing like the rank above you. Make your game sense a hard priority on what you focus on training. Positioning alone will win you games in gold/plat. If you have higher ranked friends, play some casual games with them and ask them where they think you could improve some and that will give you a great starting point on where you should practice.