My mom died at age 39 from melanoma. That was 24 years ago. I know how difficult anniversaries can be. My mom died in January and my dad died in December, so the holidays are always stressful, all of the bad memories. It does seem to get easier, though. The anniversaries of their deaths don't affect me as strongly now as they did 5-10 years ago (my dad died 14 years ago).
I know the sadness that you feel from not having your mom in your son's life. I really struggled with that when my daughter was born. When my daughter had to have surgery, I had a dream that my mom was hugging me, and I got this wonderful feeling of security and understanding, like everything was going to be all right. My mom was an RN, and at that time, I was really missing having her there to reassure me through the surgery. That might have been the reason for the dream, although I do feel that my parents are still with me somehow, looking out for me. Someone must be, because my sister and I have both done some really stupid things over the years, and we have managed to live through them, relatively unscathed.
I just wanted to give you my perspective and let you know that I understand.