Hi Jan,
I am so sorry to hear about your mother. Other than the fact that I'm male and you're female, you pretty much exactly described the situation I have with my mother as far as our relationship being very close. And, like your mom, my mom had me at a young age (19), so she is only 66 now (I'm 47). We talk every day, and, luckily, she only lives an hour from me so we see each other frequently. In fact, because my AS is so severe and I'm on full disability, she comes down to my house every couple weeks to help out with my laundry, groceries, etc. I cannot even imagine what it would be like to lose her now, which means I cannot even remotely imagine the pain you must be feeling right now. My heart goes out to you and your family, and you will be in my thoughts and prayers every day. I am glad you are going to be able to spend time with her and be there to ease her pain as much as you can in the coming months--I hope being there helps ease your pain too. Stay strong.
Brad