oh jinny im sorry this has happened. im very glad she told you though. its possible its not a problem or something to worry about but i do agree with approaching it as suggested in the post above this. just talking and listening and dont make a fuss over food or weight or anything.
would it be possible to get her to talk to a counsellor? not necessarily about the throwing up but maybe just suggest that she might want a caring stranger to confide in about anything at all that might be bothering her. then if there is really an eating disorder there the counsellor will figure that out and if not then there is no harm at all done.
i really hope this works out ok for you both. the only thing is that you cant force her to do anything. not just because shes nearly 18 but also because as you know healing has to come from within. the only thing you can do is create a space between the two of you or with a counsellor where she will feel safe enough to face anything she might need to.
good luck to you both.
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