Green can be quite normal.
Have you been on Antibiotics at all or has she had diarrhoea? Sometimes that can strip the gut of lactase, leading to temporary lactose overload and green poos (mroe sort of frothy though...).
Or else it could be a fast/foreceful letdown, which has the same sort of effect. Does she pull off or fuss a lot as you letdown?
The starvation poo that your mum is referring to woudl be dark green lumps of poo, indicating insufficient milk intake, which is not at all what you describe.

How did you get on with the breastfeeding clinic? Things going ok otherwise?