AITAH for being insensitive about my dead sister?

Long one, sorry. I 17F, have a dead sister. This incident happened 6 years ago now, but my mom still brings it up. She died at just under a month old. I had been about 6 at the time. I didn’t understand much of it at all. Being 6, I didn’t really get it. I didn’t understand how sad and sensitive her death had been. I had never met her. I didn’t have any relationship to her. I hate to say this, and I never really have, but I almost resented her, because for that year and so on, it felt like me and my living siblings meant a little less. I understand now that this isn’t right, but I didn’t then.

Fast forward a few more years, I’m 11. After my sister’s death, my mom donated lots of blood. My dad and I hate needles, but she always tried to get him to go. One day she had been extra insistent about it and in attempts to defend my dad, (Again, 11 and dumb) I said “I think it’s dumb.” (I had little idea about how blood is reused.) My mom goes “They used donated blood to try and save your sister.” I said “That didn’t save her.” or something similar (This is all just how I remember it roughly.)

She said “You are so emotionally unintelligent!” and ran to her room to sob. My dad made me apologize. I did feel bad. I still do. The “emotionally unintelligent” thing stuck, so I looked into it online. It has stuck by me since. My mom retells this story often because it’s just about the only time I’ve ever been really “bad.” She brought it up tonight through talking about how me and my siblings got flaws from our dad. I tried reiterating that at 11, I didn’t understand the sensitivity there and that I don’t believe I’m all that emotionally unintelligent. She said “You had to have. Nobody has to teach you to be nice. And I remember telling you you’re emotionally unintelligent. I stand by that.” She really does believe that I “just should’ve understood.” but I don’t believe that death is one of those things kids just suddenly understand one day. Especially not at 6, and not even at 11.

I feel like, as much as I might’ve been the asshole, (and I’ve admitted that) I’m not still 11. I understand now. I try to be empathetic but she still believes I’ll always just be “emotionally unintelligent.” I have apologized a million times over but I don’t think she sees how hurtful it is that she ignores how my sister’s death affected me too. It disrupted everything in my family. I didn’t understand it much then and nobody took the time to help me understand it. I get it now, and I am remorseful. I try really hard to be an understanding person but she still reminds me of just how apathetic I really am and always will be.

Side notes:

  1. I’m not going to ever stop talking to my mom. As much as this does hurt me, she’s does really love me and it isn’t often that she makes me feel bad, it’s just repeated.

  2. She’s never had real therapy. She has a therapist friend she used to visit briefly but she stopped quickly because she didn’t have the time for it.

  3. My dad has tried to add to the topic that at 11, I really might NOT have known better, but my mom is a stubborn lady, and my dad lacks much backbone.