Four weeks seems like a long enough time, but, in reality, you are just emerging from the "Dark Days of Recovery." This recovery takes much longer than we are ready for and much longer than we would like it to, and patience is the operative word.
Again, as others have said, while the swelling may appear to have gone done externally, there probably still is some internal swelling that you cannot see---so take the exercises gently and slowly, and continue to ice and to elevate as much as you can.
The knee is much like, as Josephine so aptly puts it, like a rubber hose filled with water---it is not going to bend easily, so just be patient and understand that the recovery will go on for some time.
You will get there---your destination of being fully recovered, but it will take some time.