I don't think it's anything you did in raising them per se. I have heard it's not ideal to be petting roosters or cockerels anyway. Me, I have one roo who is a year old, and right from when I first got him I never pet him. I walk through him instead of around him. I make him move for me. And I never let him mount his hens in front of me. He knows I am the boss of him. He can be the boss of the girls though - he is wonderful with them.
Good signs for a rooster to exhibit are things like finding food and calling the girls over so they can eat it instead of him, rounding all the girls up at dusk and leading them back to the coop, standing look-out and being aware of impending threats, gentle mating techniques and an attempt to entice the girls into mating with him - not launching a surprise attack!
My boy takes the girls to their nest boxes when it's time to lay. Sometimes he will stand by the nest while they lay to make sure they are ok. He never attacks or pecks at me or any other person. He does the egg song with the girls when they lay an egg, and will come to collect them and escort them back to the flock if they get separated.
I think your main issue is the fact that you have not one, but two cockerels. When you have two, and only a handful of hens, they will over-mate the hens aggressively in order to claim their position as leader of the flock. It's a dominance thing - "I will have you and you and you and I will have you whenever and however I want...." The rooster who gets that is the head rooster, and the other will become secondary to him eventually, rarely mating the hens and sometimes not even crowing in the presence of the dominant rooster. Unfortunately, to arrive at this scenario, it will often get quite violent first, and as several other posters have already advised - it's not a good environment for your hens.
I applaud you for the choice you have made. It is a controversial topic but one that each individual has to make their own decision for. Me, I have two cockerel chicks right now which I am advertising as Free to Good Home. They get along at the moment but combined with my existing rooster it would end badly I suspect. I don't want the chaos and carnage you've had to endure, for me or my hens. If I can't find a suitable home they too will be despatched humanely. I am not interested in keeping a bunch of hungry mouths for no return.
Wishing you all the very best,
- Krista