I don't know who are the people telling you that "you have to move on," but they're wrong. I think it's perfectly normal that you're still grieving and miss your parents. Especially, if they were your best friends, as you said.
There isn't a time limit on grief, and you shouldn't feel bad about that at all. Some people mourn for years, decades, and some can never entirely move on. The core of grief is love - and you have plenty of it. Time and your relationships will help in the long term.
I'm lucky that I still have my parents and they're similarly supportive as yours were. I can't be grateful enough for that. I can't even imagine a world without them, and I already know I will be devastated once I won't have them anymore. Embrace your feelings and memories as long as you can. You'll feel when you're ready to let go and it's gonna happen naturally.