Milk
It's OK to drink a lot of milk as long as you need the calories. Drinking calories is a good way to take in too many calories, though, and prevent weight loss or cause regain. Doesn't sound like that's an issue for you, though, at this point.
Are you getting enough protein? If you eat 300 calories a day and half comes from milk, you're only drinking about a glass and a half of milk, which is not that much. But that would only give you about 12 grams of protein. So what are you eating that has 150 calories and 50 grams of protein the rest of the day?
Kelly
Please note: I AM NOT A DOCTOR. If you want medical advice, talk to your doctor. Whatever I post, there is probably some surgeon or other health care provider somewhere that disagrees with me. If you want to know what your surgeon thinks, then ask him or her. Check out my blog.
I add my protein powder to skim or soy milk and a lot of my calories also comes from this. I had surgery the same month as you and also have a hard time getting in my calories. My goal is 1000, but most days I get about 500 this including my milk/protein.
HW-298 SW-251 Loss/Month post RNY(1)-23.5,(2)-23.3,(3)-9.9,(4)-10.6,(5)-8.9,(6)-7.7,(7)-4.2,(8)-7.5,(9)-1.7,(10)-10.8*first goal reached*,(11)-6,(12)-1.3,(13)-0.3,(14)+2.9-*changed scales that weigh 2lbs heavier*,(15)-0.3(16)-4.7(17),+5.8(18)-1.5,(19)+4.4,(20)-+4,(21)-1.2,(22)+3.5,(23)
Hala. RNY 5/14/2008; Happy At Goal =HAG
"I can eat or do anything I want to - as long as I am willing to deal with the consequences"
"Failure is not falling down, It is not getting up once you fell... So pick yourself up, dust yourself off, and start all over again...."
Priscilla 
