How do you create space as a tank?

I have been learning dive tanks mainly because they are great at contesting all possible routes on a map. Today I played a lot of Dva and I find myself always being surrounded from all angles, the enemy team holds high ground, flanks and the chokepoint while my team groups up behind me.

My main issue is I have no clue how to 1) knock the DPS off the high ground, 2) push the DPS away from flank, 3) prevent my team from having to fight the tank alone, 4) dive supports. I feel like that one Spongebob meme where I am looking in multiple places at once, but I don’t know what to do. I will assist a teammate in pushing to high ground, but then my team will start cracking under pressure so I go back to cover them, but since I abandoned my teammate, he starts losing the fight, and I am all out of cooldowns to help him, so he dies.

I tried taking the high ground then, but I will be either dived by their tank, which forces me into either a 1v1 or I have to abandon high ground which puts them at an advantage.

I especially struggle against dive tanks who somehow can 1v4 my entire team, which makes me feel like I’m playing a Sisyphean game of tag where he dives, I follow, he dives again, I follow, until he gets a pick. I try to watch out for my teammates and assist them at all times but when they are all split up and losing their individual battles I get super confused and end up losing it all.

Am I doing something wrong? I probably shouldn’t be babysitting everyone and try to let them fight their own battles but they seem to lose more than they win, at least from the games I played, if I don’t jump in to assist they will die more often than not. It doesn’t help that when I attempt to disrupt their supports their tank is always there to peel. I try to do the same thing for my supports but I get distracted trying to do everything at once.