By the posts out there you are very obviously not alone. I am sure I recall you tried before and ended up staying with it or is that my mistake?
Tricyclics are supposedly easier than other classes of ADs so ‘they’ say but then again it’s not ‘they’ that are having to do it I suspect. It’s Us. Hope things soon improve for you.
Weaning off nortriptyline - return of MAV 
I often wonder how much of our apparent hypersensitivity to meds/change or whatever is general or due to the condition not that knowing the answer would make much difference I suppose. I have recently started high doses Vitamin D on Doc’s instruction and I had a headache every day for the first ten days at least. Just an ordinary headache, not migraine but the behind the eyes, too much concentrating take-two-paraceutomol type ones. Hadn’t had one of those yet alone a dozen in as many years