It's been roughly 8 weeks since I went off Nortriptyline and I can say with certainty that my headaches are worse now than they were when I was on Nortriptyline (same with Paxil and Prozac).
For instance, I have a large ViewSonic monitor that I could use just fine on Nortriptyline but now I get headaches within 10 minutes of using it. I'm back to my old standby monitors (I have one old Acer and one old Asus that are 10+ years old).
I got a prescription for venlafaxine (Effexor). I'll give that a shot, but I have some serious catching up to do in my life, so I need to make sure my motivation issues are figured out before I start another antidepressant. I'll send an update in November.