Stuck between 700-1100 elo for almost 1 year. What to do now????

So recently I have found out that I have made 3 accounts of chess which is like 700 in rapid and 600 in blitz in one of them and 400 rapid 350 blitz in one another. I have decided that this would be my main account from now and I will not make any accounts further. Playing since 20 days (on this account) and I have noticed that the most I can make up to is only 750 and after that I lose, making my rating go down. Is anybody experiencing this?? I started playing chess 1 year ago (from April 2024). Since then I have improved a lot, but my rating does not go up. I play better otb (on-the-board) than online, and I have almost won all my games against my friends in otb. Can anybody explain the solution???????