Why did it have to happen?

That's what I don't understand. My siblings don't deal with C-PTSD (aside from my little brother). If they have, then they've never talked about it. To add to it, I have an older sibling who doesn't believe what my dad did to me was wrong in the first place.

See, according to my older sister, I was just a bad kid and 'treated dad wrong'. I won't lie, I became flat out belligerent after my mom left. Wouldn't talk to anyone or associate with any of my family. I just wouldn't for the first two months. During that time, yeah my dad laid into me a lot. Sure, I definitely said things back. I understand what I did as, 'you can't talk to a parent that way' and I got better and I learned after being forced by the school to start counseling. It took two months, two, for me to say, "Yes, sir. No, sir." and always stayed calm during those nights he yelled at me for an hour or so at a time before bed. Why was he yelling? Bad day at work and I just must've done something to make it worse.
After a certain amount of time, I want to say I was around thirteen, something new started. All of my siblings, every one of them, would be in bed fast asleep and I'd be awake. By choice, hell no. I was awake doing chores and doing outside chores throughout the night. Lay down for a few minutes, get up and get my brother ready for school. Go to school (usually tried to sleep a bit at some point during class). Go home. Clean. Homework. Make dinner for my brother. Get my brother to bed. Stay awake to open the door for my dad and older siblings 'til around 11pm. Older siblings go to bed. Dad yells at me for some time about how I didn't do something right. Makes me do chores over again and stay awake so he can rant. Get to bed around 4-4:30. Alarm goes off at 5. Dad yells at me for being tired. Get up and repeat.

^I'd do this for months on end. You'd think weekends would be better, right? Nope, I wasn't allowed to sleep during the day. It was 'bad work ethic' because, you see I'm lazy. If I slept I was worthless, lazy and just too stupid to actually achieve anything.

I have an older sibling who told me, "Dad was trying to teach you something. And it wasn't that bad, just get over it." I've brought this up on the SoA forum before because I needed reassurance one way or the other. I think that's why I'm doing it now. I would sleep so little that hallucinations became absolutely normal to my daily routine. My finger nails looked interesting. My hair fell out in clumps. And you know what, I sure became obedient after a while. It wasn't 'Yes, sir. No, sir" obedience. It was, "Why are you so stupid?"

"I don't know dad."

"You're never going anywhere. You know that?"

"Yeah, I know that."

"You're way too emotional about everything."

"Yes, I am. I'm sorry."

I wasn't just obedient. I was wrong. Nothing I thought was real and everything was in my head. What my dad said wasn't just true, it was flat out gospel.

I have C-PTSD originating from multiple childhood traumas. I never considered this one until my T said that this wasn't just abuse but a form of torture, and indeed traumatic.

Long story short and into a question: Is my T right and this is considered trauma? Is my sister right and it wasn't actually anything bad? Am I right in saying that it was wrong but I've had it worse and therefore it isn't okay but isn't trauma?

I just don't know anymore.