How to split push effectively in low elo?

So I recently picked up Jax, to increase my top lane champion pool, and unlike Irelia, he is a very poor team fighter if the enemy team has any cc. He was really good with Spear of Shojin in team fights because he could get e back up multiple times in a team fight. Riot nerfed Jax hard, then removed Spear of Shojin. They never buffed Jax back afterward. Okay so team fighting just doesn't work unless enemy team is behind, so what else can I do?

I build trinity force, tiamat, and split push. I warn my team to hold mid-tower, and not engage the enemy if they can help it. Guess what they do 90% of the time? Push past middle of mid lane and the enemy team engages them 4v5, and my team blames me. What are they even doing out that far from tower!? I don't understand why they think Summoners Rift is Aram or something. It just doesn't seem as though high silver is capable of not running it down mid. I don't even know what they are doing when they run down mid, and fight 4v5. Do they expect to win? This happens even when the enemy team has a lead, and it really tilts me. Even if I have tp up, by the time I teleport in we are already losing the team fight hard, and I just unintentionally int. I can't cancel my teleport even if I see my team running away, leaving me to die.

The rare times my team doesn't 4v5 while I'm splitting, they instead put down no pressure, and take no objectives. If they went bot lane, and they send three people top to kill me, enemy team won't be able to stop my team 2v4, and they are going to get at least 1 tower. If they don't send people top, I'm going to take a tower or two. I try to communicate with my team, but they never listen to me. How hard is it to not engage the enemy team while you have someone splitting, and taking towers quickly? If they just dug in mid-tower, enemy team would eventually get impatient, and dive them, or send 3 people top to kill me.

If Jax can't split push, and can't team fight very well, then what can he do currently? The games end so fast nowadays, and I can't even scale. For example, my Irelia is far better than Jax the entire game. She can split, and she can team fight pretty well. In all, she is much better than Jax when a game lasts no later than 30 minutes 80% of the time.

More importantly, why do they nerf champions, as well as remove items that made them too strong? It's a double nerf that really ruins gameplay for a champion. Either nerf damage of an op champ, or take away the op item, don't nerf them, and then take away the item that made them overpowered.

And for anyone that says, Jax was super op! He was way too strong! Please keep in mind, even with Spear of Shojin, a good Aatrox top would fucking dumpster you the entire game. There isn't a damn thing you can do about it either. Darius dumpsters you as well if he plays safe, even more so now unless you max e. Don't even get me started on Cho Gath, without conquerer true damage Jax can't even injure the guy. He silences you, and q pokes you every time you go for a minion. And recently I even got cucked by a Soraka top, It's so ridiculous, almost as bad as Cho Gath. Jax q is now nerfed to pathetic damage, and his ult damage on every 3rd hit was also nerfed, as well as his attack damage. but you don't see Master Yi getting nerfed repeatedly.