Giving my grandma a great grandchild?

I am one of my grandma's 13 grandchildren, the 3rd oldest to be exact. Right now, my grandma is going through some health issues and she's only 71 years old. I'm 20 years old. She already has a great grandchild from her oldest grandson, but he lives back in her country in the Caribbean. I want my grandma to be able to see me get married & have kids some day of course, but it's scary when you see someone you love go through some health issues. She's going to get a CT scan tomorrow to see what's going on. I know I'm 20, but I have a job, have a boyfriend that I've been with for almost a year and I'm going to be moving in with him in the next year or so.. He has a job and he's stable. I'm a teacher & I want to get my things stable before I can do anything, but my grandma has been a huge part of my life and I always wanted her to see her great grandchildren someday.. I'm hurt and now i feel like it may be my duty to do that for her .. What do you think?