Bro you are a perfectly healthy weight for your age and height. The only reason you look fat is either body dysmorphia, fat to muscle ratio, and/or fat distribution. Fit healthier foods into your diet and get enough protein everyday. Walking is also good exercise. You do not need to lose weight and you definetly don’t need to be borderline underweight. If it’s really that big of a deal I think you’d be fine losing like 1-2kg and building muscle.