Oh, that must have been so hard. It sounds like you were really close to them! Closer than a lot of people are to their parents. It must have been unimaginably difficult to lose them when you were just a kid.
I don't think they would be disappointed in you. They sound like really nice and intelligent people who really loved you. Not everyone fits into society's mold for success. It's a stupid mold anyway. Plenty of "successful" people have completely messed up lives, and a lot of them are either completely evil or are screwed up in other ways. Or they're actually really dumb and are only successful because they were handed everything.
You're obviously really intelligent, and you're a good person so you're not a failure. Plus, you can still become anything you want.