You will be able to best answer whether you feel overweight - eg if you are very muscular you will obviously weigh more and weight isn't always the only or best way to judge your overall health and fitness.
If you decide to lose weight you will lose it all over, and despite what some diet and exercise plans claim there is no real way of losing fat in one area alone, such as your stomach. Your body shape changes as you mature - sadly, only teenage girls have flat stomachs and abdomens. Nature intended your abdomen to be rounded and time, pregnancy and good living make sure this will happen.
You might want to take up an exercise form such as pilates that concentrates on core stability, which will help you slouch less and hold your tum in naturally. You can also get some nice strong lycra undies that help with self esteem.
Your friend's bump is caused by her womb enlarging upward and outward but pregnant tums also come in many shapes. She will be like a 'let down balloon' for some time after birth, and recovering her muscle tone will depend on her fitness and genes, but rest assured nobody is ever exactly the same after a pregnancy due to both physiological stretching and hormonal changes that afftect your skin and muscle tone. It is not a 'bad' change, it is simply a new phase of your life.