I think that you might just need to adjust your expectations. Don't quit, just realize that kids are all different, and just because Callum was trained in 2 days doesn't mean that Max will. Also, get used to the idea of cleaning up pee&poo. Just persevere, and it'll happen. Just probably not overnight like you're hoping.
I love your new family photo, that's so cute! I've got to spend me some time with your boys soon.