No, you haven't "lost" anything.
You will most likely be on an "up to 20meg" package, meaning that a) anything up to 20mbits is acceptable for your contract, and b) that you are unlikely to ever see 20mbits.
It will depend on a number of things too, like how many people in your vacinity are also on the same service.
EDIT: Consumer grade data connections are typically never at stated speeds. If you want a guaranteed service, with zero fluctuation, get a corporate grade leased line.