Is she too young to be doing this??? NEED HELP!?

OK so my 13-yr-old daughter wants to engage in natural enhancement. She'll be 14 in two months. She's very, very unfomfortable with the size of her chest and it's not like she's asking for surgery or anything. She bought a book and pretty much everything else she'll need on it, I read up on it and it appears to be safe and the herbs appear safe. Her doctor says she is done with all her growing (height, so presumably growth too). It's been over two years after she got her period so this is expected and also, on my side of the family, we are short and don't have a large bust, so I do think she may be done with growth. She's a very good student, good girl, and doesn't ask for much, I know she wouldn't abuse the power but she's been very uncomfortable with her body. I've been trying to be a good mom by saving her body from being under a butcher knife and yet letting her be confident through a "safer method". Please tell me if you think this would be the right decision, because I'm not so sure if she should mess with her hormones through natural enhancement just yet or if there is a slight chance she may still grow. I'm literally torn between the decision. Sorry for how long this is...Please help, and thank you.