You poor thing.
I remember being party to a discussion where someone mentioned her late mothers dying and how she was a bit shell shocked that it was a lot noisier and stressful than she expected, certainly not the "peacefully slipped away surrounded by her loving family" narrative that they peddled to wider family and friends, to comfort them.
Several other women agreed with her.
The movies portray death very differently to the reality that some people experience, particularly older people.
We had someone very close and dear to us die recently, and he really just drifted away very peacefully on a huge dose of opiates which were keeping him very comfortable.
His mum lost her elderly mother only 3 months ago and she remarked how peaceful it was, compared to her mums passing.
It sounds as if you loved your mum so much, she would hate for you to be torturing yourself.
I think you are in huge pain at her loss.
Try and focus on the lovely woman she was, the great mum she was, the daughter, sister, and friend that she was.
These were the last minutes of her life that were far more painful for you to witness than they were for her to bear.
Wishing you well, and hoping you will find the kindness within you, to show yourself, as she undoubtedly would have wanted.