hmmm; yea, that must really suck, but i mean if she was dying there's not much you could have done and maybe it's better you didn't go see her in the hospital because it would'e been very difficult to see your grandmother like that. Try to think of the happy memories you have of her

you just don't realize things like this until they're over, but it's normal, so you shouldn't feel too bad about it. At least you sound like you had a good relatioship with her before she became ill and that is probably most important because there's so many kids who hardly (or even never) see their grandparents.
hope you feel better
I lived in the US last year (I'm from Europe) and my grandmother ended up in the hospital about 4 times while I was away and I felt so bad because i couldn't be there with her. but now I got back and the day after I my "welcome home" party they had to bring her to the hospital again and because of what happened while I was away and I was so scared of her dying while i was gone i've been visiting her a lot lately, but just because i have absolutely nothing else to do now that I'm back in europe, if I would be busy like you were i probably also would hardly visit her... it's just tat the past year has made me realize that it's important...