I have two SW CAH boys-  my oldest always ate well-  my youngest did not eat anything.  Always 0%-5% for weight,  kind of back and forth-  at about 3- or 4 he started eating,  really now at 7 he is one of the best eaters.  He likes everything, salmon and spinach is his "birthday" dinner.  I never forced the issue-  although it is hard.  I just continued to offer good foods and limit the bad stuff.  He did always drink milk.

He is now slim but not skinny and has a regular appetitie.  I did kind of have to start limiting his snacks as I got in the bad habit of letting him eat whenver he wanted because he was so skinny.  I think he is between 25%-50% for weight in fact I think at last check his weight was higher % than his height.

If your childs levels are OK try not to worry-  it does seem to just work itself out.

Good luck to you.