Welcome to GF. Some more information, such as what you're feeding her and why you don't think she's eating well would be helpful. I will say, though, that if you think she's not eating well because you don't see her eat, as long as she's growing you're probably OK. I've had my crested gecko for about 3 1/2 years and have never seen him eat his CGD or drink water (I have seen him eat crickets). He's big and healthy.
Welcome to the GF alot of helpful pepole on here and thier care care sheets you can look at also. I also use to have crested geckos and they are great to have show us some pictures of your crested and tell us what kind of setup you have for it.