I didn't have an answer for this until I read dreemit's response. After reading that, I think your Nana made you confident and proud. Basically she made you love yourself. All we can do is our best to make the kids we love see themselves as worthy of being loved and thus love themselves.
You clearly care quite deeply. That is the best place for them to start.
I do, my nieces and nephews may as well be my own, I introduce my oldest nephew (the one with the freezie pop in the picture) as "my first born".
I am really, really trying to instil in them to love every aspect of themselves. To love the sum of all that they are, even the bits they might think are bad, even the bits that others tear them down for. At the end of the day the pixels make the picture and their photographs are beautiful. All I want as a guide for these kids is to help them to know that with confidence that reaches their core.