I'm unable to climb anymore.

So I'm Aeko, and I ended up this season in diamond 4. Highest I ever got was diamond 2 but that quickly came crashing down. I played lots of games around the middle of Diamond 4 and eventually I was too scared to try playing ranked, in fear that I would lose and possibly demote from diamond.

To work around this, I quickly got on a smurf and started ranking through the ladder. Took me around summer break to get it to plat 1 with on and off games on my main. Eventually as the end of the season came around, I strived to reach diamond on my smurf only to realize that I was actually getting stuck in plat 1. The rest of the elo's were easy. Bronze and Silver were as expected. Gold was a smooth constant climb with very little losses. But play was a different story. It was easy to climb up to around plat 2, but plat 1 was where I started effectively losing games and climbing very slowly ( relying on lp gains for every win and loss). Getting stuck in plat 1 ultimately changed my mindset. It was no longer, "This is a smurf account, and climbing will be easy". Instead I begin getting frustrated with each loss and eventually gave up on getting to diamond on my smurf.

As the season ended, I started playing on my main again, but my playing was horrendous. I lost multiple games in a row and if I was lucky able to pull a win. I really want to climb even higher this season, but at this rate I'm going to demote.

Team play in diamond is certainly better than all the other elos, but people still do the same thing. This leads to frustrating games and eventually a loss. I'm not going to blame my losses on my teammates, but I will say that sometimes I feel like I don't have a team. But the main goal of this post is to ask, "How do I get better from here? How do I effectively climb in Diamond? I've already accepted that I'm bad and need to learn so I'm hoping some of my fellow diamonds would be able to give me some advice.

With the removal of sight wards this patch, my vision game has gone down poorly, and we seem to just lose the game before I'm able to start making plays as a jungler. In lane, I usually do decent. I know how to manage waves and communicate with my team to work with teleports, and I'm also aware of how to be playing in certain match-ups.

The main issue seems to be, we lose the game before it begins. My mid laner dies once, comes back, and dies again. Now the stronger enemy jungler dominates me as I'm forced to jungle safely and farm up. Whenever I try to gank, because its Diamond, my enemies know how to play and the stronger enemy jungler completely shuts down my ganks and forces me even further behind.

I need to be learning and improving on something, I just don't know how and where I should begin.