Long term effects of Nortriptyline?

Hi! I was diagnosed with chronic daily headaches and chronic migraines when I was a sophomore in high school. I was started on nortriptyline HCL and increased doses until I settled on 30 mg. daily. I just realized that I've been taking this for 4 years! I've never had any side effects, and I've recovered from the worst of my health issues. I also think the anti-depressant was super helpful to me. I do notice the effects of withdrawl if I miss a dose, but mainly emotionally not physically. I've never stopped taking it for more than a missed or delayed dose. I also now take aderoll for my ADHD nearly every day. I've had zero issues with the two and actually found the two help keep me emotionally and mentally balanced. I'm very curious to know if there's any long term effects of taking nortriptyline for this long? Cause honestly I don't want to stop cause I'm finally healthy again. I still have occasional migraines which knock me down a day, but I shut up for a day with my pain meds essential oils and sleep it away. And while I'm still prone to minor headaches, after not going through a school day without a headache, aura or migraine for 4 years, I'm not complaining!