Only 4 pounds lost in weeks 3-5????

Had my surgery on 12/16/13. Lost a huge amount of weight (37 pounds) in the first two weeks. Partially I think because I didn't get good discharge info and drank only 2 oz of ensure 3x a day for those two weeks. But since 1/1/14 to today I have lost only FOUR POUNDS. What's up? I was willing to deal with a week stall because of my period. But I've been back at the gym at least 3-4 times a week, doing spinning, swimming, and weights. I'm usually tracking what I'm eating, but am only eating laughing cow cheese, hummus, refried beans (about 1/4 cup, no more than once a day), some protein drink (shake or isopure) at least once a. Day to get the protein in. Only thing I can think of is I've had some soups  at lunch that I have been buying out - but things like cauliflower cheese soup, split pea, cream of broccoli - but no more than 1/4 or 1/2 cup. My focus has been on hitting the protein goal, and I haven't been focusing on calories, but I'll start tracking that too. I get at least 50-70 oz of water a day too. Help! I'm obviously happy with the overall loss, but I'm starting to get demoralized if this is going to be the rate of loss from here on out...

Totally normal.  Stalls are to be expected.  You will probably see another one around three months out.

What is your protein goal? 

Okay. Stop worrying right now. You lost a butt load of weight in a very short period of time. Your body is going to do this to you no matter how perfect you are with your nutrition. I stalled from weeks 3-6. and this happened on and off for the next year. The best thing you can do is stay the course. Sometimes eating too little can be as bad as too much, so stay in touch with your nutritionist and your plans, and enjoy your progress. Remember...no more yo-yo dieting! THis is for the long run! You keep it up!!!

Protein goal is 50-60 oz/day. 

i know I'm being silly, I appreciate the reassurance! It just feels like all this work for so little progress, it just makes me anxious for when I start introducing real food. 

The standard recommendations I see for protein are 60-80 grams and then 80+ ounces for water. The soups you're eating all seem to lean heavily to the carb side of the equation, can you swap them for soups that have higher protein content instead?

Sounds about right to me.   Once you get past this staff, which is totally normal, you'll probably see an average 2 lb. per week loss.  Maybe more depending on your height and total weight you need to lose.   And up your water to at least 80-100 oz. per day, especially with the exercise you're doing.