Hi Blair,
Sorry to hear about your difficulties. At least you now know that you aren't alone. Many of us have been suffering since the 2011/2012 timeframe. I'm convinced that something about display technology changed around this time. I was thinking it was the advent of LED-backlit LCDs instead of CCFL-backlit (flourescent) LCDs, but that might just be specific to my case.
I first noticed there was an issue when I built a new gaming PC in December 2011 and got a new Samsung SyncMaster S24A850DW, which was a new PLS-style LED monitor. The display was gorgeous, but it instantly hurt my eyes when I looked at it. Even worse than just "it's too bright", the monitor seemed like some sort of mind-zapping ray of some sort. It was an odd sensation, but looking at it made me feel as if I had crammed for an exam reading books for an entire calendar day. I also had an odd ache behind the eyeballs.
Unfortunately many of us are still trying to figure out what the heck happened in this 2011/2012 time frame. My recommendation is to try to find old display monitors from like 2010 and older on Ebay or what not that are billed as just "LCD" rather than "LED". You can always connect your laptop to one of these external monitors and still use it if you find one that works. Maybe try to find someone you know that has a really old monitor that has served them well for almost a decade or more, and see if your eyes can tolerate it.
I use the Dell U2410 at work and at home at 0% brightness, "Warm" mode on the "Preset Mode" on the OSD (monitor settings), and I run f.lux software at 5000K all the time (similar to Nightshift on the iPhone). If I have the settings at default, I will eventually get that ache-behind-the-eyeballs, but it takes hours instead of minutes/seconds like modern LED-backlit monitors have.
For a phone, I use the iPhone 6S+ at low brightness and nightshift enabled all the time. I'm able to use it for as long as I need it for without too much difficulty.
So that would be my recommendation. Try to find display tech that's a decade or more older and see if that helps.