Is it normal to still feel pain 11 weeks after liver surgery?

Maybe. Depending on the incision used during surgery, patients can have pain several weeks out. 11 is a pushing the limit. I would recommend starting with physical therapy focused on stretching the core abdominal muscles. If this does not help substantially, the surgeon may need to look into it further.
Probably OK. In patients having liver surgery - particularly open surgery - it is normal to have incisional pain for several weeks following surgery. Most patients need only tylenol (acetaminophen) for pain relief after the first 2 weeks. Occasional pain with exertion at 11 weeks is probably normal. However, worsening pain, or the presence of a fever, should prompt evaluation by a doctor.