Bronze player looking for legitimate help with carrying/communicating with teams who lose lanes

Hey everyone. Before you take one look at the title and downvote me or comment "lol git gud bronze noob", let me explain my situation.

This season, I did very well in my promos, winning 7 or 8 games out of ten (I don't remember exactly). Since I started playing ranked at the end of season 6 and ended up bronze I, I was placed at bronze II. Fair enough. After hitting around 90 lp in bronze II and about to get bronze I promos, I went on a HELLA long losing streak. Although I did everything I could to stop my mmr from tanking, like not playing more than 2 losses a day to untilt, communicating with team, and picking champions I did well with, I couldn't stop myself from losing 10 games in a row. Although I admit I fed in some games, around half I went positive or even got fed while my team was negative or even. Then, after being demoted to bronze III, I quit ranked for a while to improve my skills in normals. I watched videos, read hundreds of guides, learned meta champions, and did everything I could to improve. This ended up helping me a lot, as I was able to break my losing streak and things looked like I would get silver by the end of the month. However, although I usually didn't feed in my games and did quite well in some, around 4/5 of the time 2 or more of the other lanes fed HARD. I tried communicating when things started to look bad, using pings and chat to tell people what I learned that they should do to take back their lanes + the game, but they either didn't listen, got mad, fed harder, or spammed "ff 20" in chat. I was constantly winning, losing, losing, winning, losing, losing, until my lp dropped to 0. The last two games I've played have shown me either 1. I have no idea how to help losing lanes or 2. helping losing lanes in bronze is impossible and games are lost from champ select. Although my kda, farm, and play was consistently good in both games, I wasn't able to 2v8 with the one other decent player in my game. In the first game I played, I chose to give our team late game power. Too bad we weren't able to reach the late game because the enemy was 10/1 by ten minutes. Although I communicated with my team, got picks, and tried to deter against fighting twitch, he was simply too powerful to ever hope taking back the game. In the second game I played, I picked because would have been a poor matchup against the enemy mid's choice, . Although going even in the laning phase, I was able to improve my kda and help my losing team by using my ult to pick out of position enemies. However, our decided to afk 5 minutes into the game and the rest of my team was negative kda, so we lost just as quickly. Thanks to these wonderful teammates, I am now bronze IV. The thing is, I once played a game where literally every person on our team got fed and the enemy had a massive comeback and was able to win despite the fact that they were behind 20+ kills. In conclusion, can any player tell me how I'm supposed to win these kinds of games and what the people I'm playing against are doing right (and what I'm doing wrong)? I'm willing to do anything to improve, so please give me any and all advice.