Hi, a birds colour will come through as soon as it fledges, it may darken in colour after it moults but the basic colour will stay the same.
Your bird is not a baby, i.e. under 3 mths but it's hard to tell how old she is but looks like she is coming into or going out of breeding cond..
Depending on the mutation etc the weight does not really decide the age of the bird.
I have more photos if you want to look. I know she is still motin. And her eyes has the Iris rings. It was black,now its gray now.