Most Helpful Girl
First off you're not old. I also think a lot of actual older people would look a lot more attractive if they didn't dress that way e. g. Men in their late 40 or early 50s with kaki shorts that don't go down to their knees and t-shirts tucked into them. Even worse if they have a gut.1
Most Helpful Guy
Nothing wrong with A&F at your age.
Footwear makes a huge difference to how mature something like a hoodie and jeans looks. You can wear your standard ambercormbie outfit with a pair of Chelsea Boots and it'll look age appropriate and great.