There is a chance it could be due to very fine, thin hair, but even then I know a lot of people with thin hair who still have thick bangs. I would definitely talk to your stylist and let her know you want thicker fuller bangs. It may just be because she’s not taking them from far enough back. The thickness of the bangs depends on where you part them before you cut. If you part them farther back, and then cut them they’ll obviously have more hair and be thicker, but if you part it closer to the forehead and then cut, they turn out thinner.