NEED LOOKS MAXIMISING ADVICE PLESSE FFS

I'm a 18 yr old male stuck at 5'6 idts i can increase my height I'm from a middle class brown family ,but i have a very very gorgeous and hot gf i want to make myself better and look better because i want to wife her up ,i don't want to make her feel bad for dating me ,i do think people think she is easy to get because she dates me and she is going to college this year ,i don't want her to feel bad for having a bf ,i don't, i want to improve please help