I need help

So Im a toxic little kid, and Im well aware of it. When in game I get pissed off easily. Now, Im not this way in real life or something so it isnt a medical problem/mental problem, its just when I play league. I have been through more than 450 games with chat restrictions, and I started playing one year ago. 450 games is probably most of the games I've had. I have had a 25 (maybe it was 35 I cant remember) ranked games restriction, and still need 12 draft wins to finish it. I was banned for 2 weeks a month ago. Yesterday I had a game where I was jung udyr (nothing out of the meta) and I went into draft. Was first pick, did good bans, was all good. And then, 4th pick picked irelia (even though 3rd pick was teemo top) and said in chat "TROLL BOT". I didnt react, to see if hes trolling and will switch a champ the second before it locks him in. Well he didnt. And last pick picked Heimerdinger botlane with her. So my team was Teemo Top, Udyr (me) Jung, Kata Mid, Irelia and Heimer botlane. The game started, and I get first blood on the enemy jungler. I go bot, get a good gank, and recall. During that time, our kata gave their Diana 3 kills. I dont know if kata picked herself into diana or the other way around, but when youre second pick you probably shouldnt pick kata unless their midlane was first pick, as its too risky. But kata fed. And fed. And went bot, and fed. Its not only she fed, she didnt listen either. Diana was building Abyssal Scepter, and so I told kata to either buy it too which I think is a great idea, or buy some Magic Pen. Well, she didnt. She built ludens echo. I dont remember at which minute, but when she was level 9, after feeding mid to the point where no one can 1v1 her and she's 10/1, she left the game. I was SO PISSED. Botlane was doing shit and fed vayne. Toplane was even, and Xin was getting fed. And we also had to handle a super fed diana, all that in a 4v5. So it pissed me off and yesterday while in draft lobby with the enemy team xin (he was being nice after the game), I suddenly get a message. I was banned. 2 weeks again. Now dont get me wrong, I LOVE this game. But I feel like this system is just... stupid. I dont think that real people couldve seen those reports (even though no one said he was gonna report me or anything), since the ban was 2 minutes after the game. I dont know what IS the tribunal, but I feel like this whole system is broken. When the ban is over Ill probably find out I have more chat restrictions or something.

So thats why Im here. Not to talk about the tribunal. Im here to ask YOU guys, how to stop being toxic. I really do need help, as I even tried playing with /mute all but I still write shit at my teammates. I need your help, to make me a better league player. A good part of the community. Im 13 and a half years old, and I dont want to be toxic anymore. Hope someone takes their time to reply to this, just like I took my time to write this.

Thanks