PreOp Dieting-Scale Moving Up Not Down WTH!

I have been on a preOp diet since Thankgiving and so far have lost 25 pounds. My surgery has been approved for March 17th but my doctor says I have to lose 14 additional pounds before that date. I have been following weight watchers (which has been approved by my dietician) following it closely, staying within my allowed points for the day and not using the extra weekly points but the scale is not moving down. In fact, it has moved up 3 - 5 pounds I recently injured my back and have not been able to exercise and have been taking NSAIDs and muscle relaxers but I wouldn't think that would have anything to do with it. I am baffled. I am talking phentermine and topamax and it worked like a champ for the first month, but this month nothing. I am so discouraged and worried that I will not make weight in time for my surgery. I even went to counting calories instead of points to be sure that I wasn't fooling myself on my intake and I am talking in approximately 1500 calories per day. Is that too much? Shouldn't I be seeing some weight loss? Has anyone else had this problem? Could this be a plateau? Any suggestions would be welcomed.