Only 2 lbs in a week?
Your initial losses are fluids: water, fluid in your tissues, IV fluids from the hospital, etc. Initial losses are always fast and peter off quickly.
Typically, people who did not lose a lot before surgery lose a ton in the first two week**** a plateau as their bodies adjust in week 3-5, and then begin losing again at a slightly lower rate. Don't panic, it'll happen!