My Fuzz who is nearing 11 years old had a complete front right leg/scapula amputation on 9/20/19.  He was started on gabapentin several weeks before the surgery to help with pain and received around .75-1 cc per day.  After his surgery he was sent home with continued gabapentin at the dose of .5 3x per day, a fentanyl patch on his neck that was removed by me on day 5 and  2 days of anti-inflammatory pills that he took once daily crushed in his food.  As we have seen on this site, every cat is indeed different in their recovery and there are so many factors starting with overall basic health and age/activity level prior to surgery.  I think I have missed circumstances of your cat's amputation.  Fuzz had cancer and after lab results came back after surgery he was diagnosed with scapulary osteosarcoma.  My Fuzz was a trooper and was up and about literally the day I brought him home.  He had one day of "crash" about the 4th day home where he preferred to lay in corner of his recovery room and not move around much.  Outside of that he was up and moving around, using litterbox ( I bought the disposable kind and a low walled kitten size and kept puppy pee pads all over floor of his recovery room.  He ate and drank like a trooper and I kept dry food out but he ate multiple small meals per day of wet food so I could mix in his medications.  His staples came out on day 10 and at that point he was running around like crazy.  It is my belief a rear leg amputation would be more difficult due to balance and weight bearing so that adjustment might be part of it.  You know your cat best and if you think it is beyond some pain (gabapentin if dosed correctly) and the metacam should absolutely be helping with pain.  If you believe she is in pain or not doing well then definitely reach out to the surgeon/vet and share your concerns.  Without knowing more background/length of time and specifics about being "knocked over" I would just suggest contacting your vet/surgeon and sharing what is going on/concerns!