I think that being the child of an addict is a very complicated situation.
I don't know if this resonates with you, but my dad was a functioning alcoholic but I have similar haply memories of doing lots of nice consistent things and having a safe little life. I didn't have as good a relationship with my mum because I found her to be very stressed and snappy a lot of the time, whereas my dad always seemed so and laid back and gentle.
As an adult, with my own family, I realise how skewed my perspective was. While I know my dad was kind to me, as an adult, I think what I struggle with is knowing how I wouldn't be able to look after my DC while inebriated. I know that it was very risky behaviour on his part, and it does shape some of the things I remember - for example, my dad used to have a nap (just me and him in the house, I would have been tiny, pre school age) in a very specific way, and I realise now that it was because he would need to lie down after drinking. I would feel so guilty if it was my child in that position.
I guess being an adult and knowing the reality of the situation sheds an alarming light on your situation.
It's not that you were actively neglected by her as you clearly weren't, but you know now that she was living a high risk life and therefore dragging you into it. Anything could have happened to her, she was bringing you to the park with other addicts and the drug scene is just full of unsavoury characters. She could have overdosed or lost her grip on the situation so easily. She could have triggered social services involvement and had you removed. You recognise this now.
I am so glad your mum had the foresight and ability to keep bad men out of your life and to keep things together. That's what my dad was like, he may have been drunk every day but what I remember is taking our dog for a walk every day, reciting a story every single time as it was depicted in stones along the way (we were going to the shops to buy beers!), making fresh bread from scratch, watching Disney movies etc.
But it definitely doesn't always work out well. I'm not sure what the answer is to be honest; my dad passed when I was 27 and I loved him but sometimes I do feel angry. He put my mum in a difficult position; she worked herself so hard in a high paying job as my dad didn't work. She was so stressed and snappy with us all the time because she was so busy all week and then had to spend the weekends cleaning. We lived literally a street over from the school, but my mum told me she would have to leave work to pick my eldest sibling up from nursery and bring her home, then go back to work.
This was the 90's, I think things were just seen differently. Only when I was much older, pregnant with my second child, my mum recalling the time when the headmaster of our primary school had taken my dad to one side as he had obviously been spotted drinking or drunk many times, and saying "the other kids are alright, but you can't do this with [me], she is too young".
I never confronted my dad about his behavior, nobody did. There were also other issues in my case, which colour my perspective further, but I honestly don't know what the best solution for you is. Maybe therapy to process your emotions? I just live with the feelings tbh, and let it guide my judgement with my own kids.