How the hell do I beat lorian and lothric?

I have never been this stuck in dark souls. I beat dark souls 1 a couple years ago and decided to give dark souls 3 a try after I couldn’t get into 2. I have gotten through 3 fairly well. I get stuck sometimes but I usually just figure out a strategy or lock in and I get through it even if it takes several tries. I have never been so stuck in dark souls before, maybe gaming in general.

It took me a few tries to beat lorian alone, so imagine my surprise when his stupid ass brother joins the fray. I can usually get through the first half of the fight fine. Sometimes I fuck up but generally I can do okay with lorian. Not great, but I do okay. But as soon as lothric joins the fray I’m dead in seconds. At first it was the magic he shoots when he spawns, but then I got past that. But now it’s just the sheer damage. I can’t survive long enough to hit them more than once if at all. Lorian goes insane in the second half, more damage, more speed and more aggression.

I grinded for souls to level my stats, I switched to an easy to level sword that I could make a lighting sword and did worse. Finally I switched to the great sword that looks like the one from berserk. I do decently enough with that one. But I don’t know what the hell to do.