My condolences. Sorry for your loss.
The could'ves and should'ves will drive you crazy. They drive me crazy everyday.
I personally think after a certain point I think many flatout give up. Her choices in life helped lead her to her final destination. At least she's at rest. Her story and your story are already benefiting people since you have posted it. If nothing else at least you know your final attempts worked, let others know how you did it. Mum probably even realized this.
Stay strong, Best Wishes.