Oh dear, I'm lost for words.. I came here as I saw your post from today and it was linked to three other posts which I wanted to read first. I can read in this whole post how great your mom was and how much you loved her. She has done a wonderful job raising you, it shows in every word you speak of her.
I'm heartbroken for you that you don't have more time to spend with her to make memories. I wish there was something I could say to make it easier, but there is nothing..
My mother died last year, sadly we were estranged due to the ex I told you about, therefore I had not possibility to even speak to her when things were bad, I had no clue. I got the message after she passed through a friend of her who was informed. Even without being close to my mother, it still feels as if a part of you is gone, and I can only imagine how hard that must be if you have a great bond for life..
I'm crying for you reading this.. Stay strong sister <3