I can't enjoy this anymore!

When I first played Overwatch I got ranked at 2250. In the year I have been playing I have fallen to 1500. I haven't won a game since August 2nd and I am sick of it.

I play any hero I am asked to, I am friendly and dont get salty, I communicate and I am feel like I am a good player.

So I went about and redid my placements on my brother's account. I got 2987SR. yeah...

So I got into platinum, but on my main I am in silver and cant get out.

I really want to get better at this game but I cant. My teammates dont communicate, are complete shit, never change heroes, try to 1v6 the enemy team and are incredibly mean and toxic.

My loss streak is at 18. Please can somebody help me. Literally anything - advice, strats, tips.