How is your exercise? I wasn't hungry the first couple of days post op - I attribute that to the surgery and accompanying gas from the surgical procedure (apparently we're filled up like balloons...) but my hunger increased in line with feeling better: the better I felt, the hungrier I've become. I don't think I lost any weight after the first day, but since then - 6 days later, I'm down almost 20 lbs. My only advice is - keep a 'liquid' journal for a few days and call your Dr with the results - have them confirm you're on the right track, and try to up the exercise as much as you feel comfortable with. At the end of the day, weight loss is a simple science - burn 3,500 more calories than you consume, and it's 1 lb gone.
Good Luck!