My concern with trying to force your bowels to clean is you will interrupt the smartness of your body.
If your body hasn't cleaned out your bowels there is a reason. Often it is because it is doing something else in your body first. If you body is trying to correct a major illness inside your body then it will not use all the bowel food first. It knows how to conserve, and is using what it needs.
I find that sometimes during a Water Fast if you switch to a 24-48 hour dry fast your body will work to eat up everything useless inside your body first before it starts on things it needs. It is an hierarchy system.
Forcing your body to empty the bowels concerns me because you likely have something more serious it is trying to repair first. An enema will need a lot of energy which will be pulled from other internal sources.
Try the dry fast and see how you feel by Saturday.