I also grew up in an abusive home–but I had a freeze/flee response to conflict.
So, there are several “defense” tactics when it comes to conflict. Fight, which you grew up with. Freeze (do nothing and hope they don’t notice you), Flee (leave the situation), and Fawn (people-pleasing).
When people say not to be a people-pleaser, they are generally talking to people who have an oversized urge to please as their defensive tactic. If you are a person where “fight” is your go-to, toning it down so you can properly interact with people isn’t a bad thing. It’s what YOU needed to do for YOU to gain necessary social skills.
But other people out there have “Fawn” as their defense mechanism. That is to say, whenever there’s conflict, they try to placate other people as their technique to de-escalate. And this becomes a situation FOR THEM where they erode their own boundaries trying to please other people whenever in conflict. It becomes a problem when other people take advantage of them because they tend to fawn and give other people things too much, and it causes harm in their life where work/spouses/friends abuse their placating nature. At that point, people who “fawn” need to try to do what you did with your fight response, and set more boundaries and say “no” more often without placating.
A good portion of “general advice” on the internet does not point out that “context matters”. But it really does, the patterns and personality and past of the person taking advice matters, and when it comes to someone who grew up in an abusive home learning how to master their defense mechanisms, different people will need different advice.
If you were truly as belligerent as you say before, I’d be honestly surprised if you over-corrected to the point of people-pleasing becoming a detriment, as it’s extremely hard to shake these things. They almost seem to be inborn personality traits that are ramped up into extremes if one is in an abusive situation. I have a friend who had a journey similar to yours, with a “fight” defense mechanism mode, and he’s done a TON of work breaking the “fight” response, but you can still catch him in moments where he goes into “asshole mode”.
And I’m the same, I’ve grown and improved, but I still default to “freeze” or “flee” in conflict situations that are especially stressful. (My growth has been embracing a “fight” response when necessary, and also a “fawn” response when necessary.) Him and I made opposite journeys…I learned to be more aggressive because it was necessary, and he toned his aggression down (because it was necessary to avoid driving away people he loved).