I don't remember who said the follwing, so I'll just say it as I remeber it.
How many more years do you think your parents will live? 10? 20? How many times a year do you see them? 1? 2? So you don't have 10 or 20 years more with them, you have 10 to 40 more times that you will see them in your lifetime.
I expect less than 5 here, so yeah. Time to go visit.
You can't do anything with the past, but with the time you have left, you can REALLY make it count so that one day you wont regret a bunch of things you did instead of spending time with her.