I too have a love/hate relationship with my feet (tho mine are wide and flat) and been doing the "boot dance" for many years. I am 56, very fit, and hike frequently. However, one of the changes that can occur as we get older is that our feet can get longer and wider. Ligaments naturally stretch and this enlarges the feet. And if you have had a bad bone break in your foot (as I did this summer while long-boarding with my son - Yah, yah, I know about "too old" to be on a skateboard...) your body releases a hormone called Relaxin that can further the expansion of your feet (see here for an article from Cleveland Clinic - https://health.clevelandclinic.org/shoes-getting-tight-feet-change-size-time/ ). Blackened toenails are a sure sign that your toes are slamming into the front of your boots, likely and especially on the downhill. Do look into a 1/2 size larger, but beware - Make sure that you get a boot that will fit snugly enough around your heel area to avoid boot movement and blisters. I wore Keens for years, but recently, after my feet changed sizes (yes, the skateboard, I know, I know...) I picked up a pair of Lowas, 1/2 size larger, that allow me to really dial in the fit for various areas of my feet. True, they were almost three hundred dollars, but my feet have never been happier. To get an even better fit on the trail, I have an old sock trick: At the beginning of the day I will wear a thick wool sock with my liners, and by the latter half of the day (when my feet tend to swell up) I switch to a thinner wool sock and my liners. That way, my feet do not slide around inside my boots (1/2 size bigger) and all is well.
Hope that helps and good luck.