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LW, I felt some of the same anxieties that you mention in my early 30s (I'm in my mid 40s now). I also had some 'lost years' and wondered about my parents getting cancer, which also runs in my family, or giving them grandchildren. What happened over time is that I was divorced, I learned I could not have children, and now I am the one with metastic cancer and they are caring for me.
I am learning, very slowly, painfully, but learning, to appreciate what is and not to anticipate future problems. Sure, it's always a good idea to work on your relationship with your father. Do it. Use prayer, or whatever spiritual discipline you have, to let you of your anxieties, and for heavens sake, stop mediating yourself with booze, I've also been there and done that!
But remember there is a great deal in life that you have absolutely control over, and enjoy the moments you do have with your parents. Tomorrow will reveal itself, for good or ill.