Congratulations on this work! I think is excellent.
I agree to some point to the proportions issue.
I think proportions don't always have to be the same. It's incredible how the little differences between one or another humanoid can give him/her a different personality: lower or higher mouths, eyebrows...
But in this case, breasts DO seem lower than one could expect from a cool chick

The personality in this case is of an older/ uglier woman.
Fortunately, 3d model adjustments are a lot easier than breast surgery.