Unfortunately, side effects like suppressing appetite don't apply to everyone. Most people have to consciously make a dietary change to see weight loss, regardless of what medications they are on.
So you begin by...making a decision to eat less, and trying to achieve that each day. And if you eat too much one day, getting right back on plan the next.
It might help if you set out a plan for yourself. Write out what you intend to eat for one day. Stick to that plan. Repeat.
Breaking the cycle of overeating can be tough, but there is plenty of evidence here at 3FC that it can be done.
Good luck!