1. The coil springs hardly go bad. They either break or the rubbers on the top and bottom get broken or splayed out. In the later case you simply change the rubbers. If a spring droops a little bit it can be adjusted by using a spacer to get an even height on all 4 wheels.

2. The suspension geometry differs from car to car. All have a balance, with heights varying from one make to another and the set up as per the performance required from the car.

3. According to your description, the shocks seem to be worn out and would need replacement. All the symptoms point in this direction. With new shocks, your height may even come up very slightly and your complaint about driving over uneven/rough roads will also be rectified.

Go ahead and change your shocks, guarantee it will sove that annoying bumpy ride.