Elizabeta,
It sounds as though your mother is progressing nicely. My husband had his mini Whipple April 29, 2009. After about 4 to 6 weeks, he was feeling good and exercising, golfing, and eating pretty much what he wanted. He had lost about 35 pounds at this point. He takes enzymes (Creon 20) with each meal to aid in digestion.
Eight weeks after surgery, he started chemo - Gemzar once a week for 3 weeks. This wasn't so bad. He had a rash and was a bit tired. He had a week off Then he started chemo and radiation together. He wore a 5-FU pump five days a week and had oxaliplatin in the oncologist's office once a week. Radiation was five days a week also. The chemo is supposed to make the radiation work better. This is all to prevent a recurrence because they think all the cancer was removed with the Whipple. He had a small 1.3 cm tumor (adenocarcinoma) at the head of the pancreas. One lymph node was involved but no other spread. They caught his cancer very early. After two weeks of the chemo/radiation regime, he started getting extreme fatigue and very bad diarrhea. He hardly could eat at all. He lost another 15 pounds. He is now finished the chemo/radiation and is starting to feel a little better. He still has no energy and cannot take a walk or exercise. He gets frequent stomach pain and gas and needs to take pain medication. It was a very tough time.
We hope the decision to go through this was the right one. Only time will tell. We see the doctor again in a couple of weeks. More chemo will be in his future - hopefully, the Gemzar which he tolerated well. Good luck with your mother. She will need you for what she will be facing. My husband just turned 70. He is looking forward to golfing and doing all his regular activities soon.