No I mean you can be fat and not necessarily look it because you're maybe tall for example. Your note read to me that I have a belly and chin but I'm 11.5 stone. If you said to someone I am 11.5 stone and average height they wouldn't assume you were fat. But your body composition could tell a different story.

You need to stay around the same weight(or more or less depends on you) but change your body composition. If you don't want to get any heavier then by changing your diet and doing some exercise, you will change your body to more of a leaner composition(you would probably loose weight here though). Alternatively, if you went to the gym and lifted weights, as opposed to long walks, bike rides etc then you would probably maintain your weight, but your composition would change. You would effectively get "leaner" with a higher percentage of lean weight and a lower percentage of bodyfat.

Hope this helps.