21 and thinking about a baby

My mother is 42, she looks healthy on the outside but, in the inside she is 78. Every time she visits the doctors , she gets diagnosed with a new symptom. She seems to be getting worse and sometimes she worries she won't be able to enjoy her grandchildren when that day comes. I'm afraid if I wait too long to decide to have a child she will be too sick to even get up and that's how she's been aren't now a days. I want to give her that grandchild. My mom is my best friend and I want to be able to share an experience like that with her. Cancer runs in my family and their is mornings and days where she is not herself and is too weak to even get up. Should I plan on having a baby ? I want to have a baby , but the question is , should I now? I don't want to wait long when things get worse with her, I'll regret it and beat myself up for it knowing that I could of shared an experience like that with her.