Well, I've felt like an old gran since I was 6 so 'old gramma' would never be an insult to me :) Even though I have no kids and thus can't 'technically' be a grannie, I like garden puttering, cracked tea pots, sleeping cats and watching the day slide by.
That's Gramma enough, who needs the kids for the full picture!! :0D
@winstonalden and I always joked if we could just go straight to grandchildren, we'd have done it. They get to spoil them and then hand them off, we just didn't want the parent part with nappies and crying. ;)