Toddler hates diaper changes

My 18 month old absolutely hates diaper changes. I’m a teacher and ECE and even I’m at a loss here. For a while having something to play with, or singing or silly faces helped. Then I made sure to give him lots of warning (with confidence) that I would change his diaper. I have asked him to help me with wiping. I have let him get changed standing up. He screams and barrel rolls every time. Last weekend, on a bad day I finally lost it. I yelled at him and held him down while I changed him. Now he hates diaper changes even more (I don’t blame him. I cried and apologized - I felt awful).

Does anyone have any ideas? We are reading about the potty and I offer it to him without pressure but he doesn’t want to use the toilet yet either.