Green Poo - EBF

Lyla
I am really after some help and advice. 
My baby is 13 weeks old now and I EBF. 
For a few weeks now her poo has been green. To start with it was very watery and I thought she had a bit of diarrhoea. 
It isn't as watery now but still green. 
We have the odd yellow poo. 
She poops a lot, always has done. Probably around 10 times a day at the beginning but now maybe still about 6 times in 24 hours now.
She has never had a good latch and had her tongue cut because of tongue tie. I try to get her on properly best I can. 
I'm getting really concerned now she isn't getting the goodness she needs. 
Any advice on what the problem could be and what I can do to improve this?
I don't want to have to give her formula but I will if I need to. 
She is gaining weight well, is happy and from what I can tell is healthy. 
The last couple of days she has wanted to feed more often again which I put down to normal growth but maybe this is a sign that she isn't getting enough full fat milk. 
I will take any advice that anyone can give please as I'm getting worried now. 
Doctor just said she is gaining weight so she is fine but I've read that she can still gain weight and not get the goodness.