Stop blaming your team.

The only thing you can affect is your own play, so improve that even further.

Emotionally strongh people don't waste time and energy on things they can’t control

Your attitude can change the outcome of the game, encourage your team and don't flame them, you will win more games like that.

I mean if anyone should be mad about that game ... it should be the dusa. 6-2-15 and 360cs and he loses, that has gotta suck.

To be honest you did badly that game, your CS was bad and you died way too many times as a hero with insane mobility, that game was your fault and dazzle's fault (positioning issues) that you lost.

You've got through half the battle by identifying the problem, now we can fix it.

I have gained practically zero mmr in 6 months despite my skill going up and up

This is a misconception. You need to improve more than every other 4.7k player if you want to climb, not just improve.

If you get angry at a team-mate you need to be constructive, "dazzle can you please stand further back in fights", "team i really need the courier for my bottle".

There is a reason you are in low prio the whole time, it's because you rage and flame.

Now try and tell me with a straight face if you really think raging helps you win the game?

No, it doesn't. If you REALLY want to climb, then you will realise the only way to get there is with a good attitude.

You should also realise that even if you truly worthy of 5k you will only have a 55% winrate in the last few hundred mmr to get there, that means 11 wins and 9 losses for every 20 games.

Normally it's 40% games you win because of your team, 40% you lose because of your team and 20% are down to you.

My comment is a complete mess but I made some good points, read it over a couple of times.