Actually you're not. The adequacy of your weight for your height is calculated by your bmi or body mass index. It's basically weight in.kg divided by the square of height in meters. Accordingly you are 23.5 and you're doing ok.Maybe you just need to get fit.
Don't forget that muscle weighs more than fat, the scales might say you're 65kg but it's best to work out what your muscle to fat ratio is but like Nimsdb said you're BMI is 23 which is quite healthy with ideal being 21
Muscle doesn't weigh more than fat... a pound is a pound, no matter what it consists of. It's just that muscle is more dense than fat, so a pound of muscle takes less space than a pound of fat...
Depends on ones muscle:fat ratio, I think. I'm 18yo 181cm and 64, feel quite fat now, but want to be 58/59, it just feels better and lighter
Follow your feelings:)