I play on Switch, but there doesn't seem to be any real version difference so here is how I beat him

The specific attack that was destroying me earlier was the one where he sinks in a tighter and tighter ring around you, in a sort of triangle shape. I found the fight much easier once I realized he leaves space for you, so find the safe spot and wack away

The other tricky part IMO is when he just pokes his head out and launches acid, just playing less aggressive here and focusing on dodging worked well for me. I could get a few hits in most of the time, but prioritize not getting hit since everything else he does just involves standing not on top of him to avoid, meaning it is easier to focus on dealing damage then

As for the random paths and red line indicator attacks, make sure you aren't on him then cheerfully shoot him a ton while he travels. I think the most he reacts to you the whole fight is targeting you with the red area, so once you aren't in reach you are safe that attack

I'm sure my strat for the adds isn't good, but I ignored them. If you are near an egg or baby, kill it. Otherwise, they won't hurt you til it gets close, in which case kill it then. They can't really body block the boss, don't have range attacks, and aren't tanky enough (this is the thing I think would have been most likely to change in a quick update) to become a big issue even when they are next to you