We have no way of knowing how much visual attention you lavish on her. But it might be worth a shot to dial it up a little, just to see. Even though I'm not feeling insecure, it still makes me feel good when my fiance ogles me. And I surely give her some visual appreciation of my own every chance I get. It can be especially fun in public.

That might not be the solution to your issue, but there wouldn't be any harm in trying, and it just might do some good.

EDIT - In fact, thinking about it, this is one of the things I love about my own relationship. The way we constantly and shamelessly check each other out, both in public and at home by ourselves.