I think people who have had Whipple surgery almost always face digestive issues. Also, I should mention my surgery was Nov.27, 2002. One of the big challenges going back to work was fitting in the small meals throughout the day that the doctors recommended. Mostly it was that I just was not hungry. You get busy, and it's easy to forget to eat.
The doctors at first did not think I would need pancreatic enzymes to help digestion, so for the first six months following surgery I tried following the recommended low fat diet trying to find foods that worked for me. Still I was unable to digest food properly and continued losing weight. Once I started taking enzymes with meals and snacks, I find I can eat almost anything I could before surgery. Have to watch peanuts and I cannot handle caffeine at all.
If you aren't taking enzymes already, have your doctor prescribe them. The improvement in digestion will help your energy levels as well. Extreme fatigue can be a result of high blood sugar. If your doctors aren't checking your glucose levels, you may want to ask them about it.
Best wishes.