It isn't wrong, but it is not standard English, either.  In standard English, 'want' would be a stative verb here, used to describe a state rather than an activity. The 'correct' form should be She doesn't want to eat any more.

That said, the non-standard 'She is not wanting' may well be  acceptable among English speakers in Bangladesh.  I'm aware that continuous tenses are often used in the Indian subcontinent in contexts where standard English would use the simple aspect.