5DPT-Slow Weight Loss-Not Enough Food?

This is my second week doing the 5DPT.  I did it Mon-Fri last week and the scales said I lost 5lbs.  I had a family get together this weekend and on Sunday I ate a small piece of fried chicken, mashed potatoes w/gravy, corn, green beans, small piece of cake, small piece of pie.  That is all that I had all day.  So this week I am starting the 5DPT again.  I got on the scales this morning and instead of a 5lb loss I had a 2lb gain.  That is with being on 2 days of liquid protein.  I am also having my monthly visitor so I don't know if that is contributing to hardly any weight loss or not.  I stuck very well with the 5DPT last week and felt really good! 
How much should I expect to lose on the 5DPT?  Has my body gone into shock and is just holding on to the weight?  Also, what is the maximum daily calorie intake so that I lose weight (I'm 5'6"-165--want to get back down to 125)
I started taking Cymbalta (antidepressant) almost a year and a half ago and I have gained a lot of weight.  The doctor warned me of this but this is ridiculous.  I could easily cut back on food and drop weight now I can starve and not have the scales move at all!

Any help?  Any suggestions? 
Thanks!

I have done the 5DPT several times, and hardly ever lost much weight, It is not about weight loss,,thats not the purpose of it, its to rid your body of cravings, and reset the sensitivity of the pouch so that you feel full with less food .
Whenever we eat a lot of carbs, the carbs cause immediate water weight gain, you can expect it every time,so always flush with a lot of water for a few days afterwards. Usually the carb cravings will start in again too.
 You would have to consume 2500 calories to gain a pound of bodyweight.
One day at a time,,,

Blessings
Betsy

The point of the 5dpt is not weight loss... its a pleasant 'side effect' for many - most of the weight you lose in the beginning is water... due to the lack of carbs your body drops water weight, oever the weekend you ate carbs (as well as salt, sugar) so your body is more than likely holding back onto some of tha****er. Honestly I wouldnt have any expectations going into the 5dpt, I personally did the 5dpt a while back and any weight I lost during the week came right back the following.
Its hard to say what your maximum daily calorie intake should be - what does your surgeon/NUT suggest? I say this over and over but will say it again - I suggest getting a metabolism test to find out what your body needs - they will show what you need to eat to lose, maintain as well as gain weight based all on your personal metabolism. You will have to find out who/where in your area provides the test, for resting and exertion it typically rusn 100-150$ and isnt covered by insurance.

As a side note I would aim to get to a healthy BMI/weight that you can easily maintain.. while you may have been at 125 at one point with the Cymbalta and regain some experience (average is 10%)  you may have to adjust your new goal to something a little higher... I would just set mini-goals and adjust as you feel comfortable!