I've been watering about every week or two depending if we haven't had rain lately.

This photo was from about two months ago, showing where new growth is occurring

some lower leaves have spots on them (possibly related is my recent post on my Mexican Buckeye that has spots on the lower leaves)

and I dug around some more looking for more girdling roots. I'm not a tree expert. Are these two roots by my finger girdling roots that I should prune now that fall is starting soon?

What's with all the suckers around the base? You don't normally see that on an oak, do you?

After leaf drop your tree needs some skillful pruning to get back on track. A picture of bare tree with no leaves would be invaluable to others on forum to give you pruning advice.

Picture of base seems like tree with decent girth, picture of top almost seems like different tree........

That's what the arborist was concerned with last year, too - the suckers or growth out of the base. He asked me to look for girdling roots, which is what I did, and growth started occurring at the top branches.

Local guides for this tree say that it is semi-evergreen with leaf drop in the spring. I believe that this is the time of year to prune and/or plant as root growth will begin soon. I'm not native to this region though.

Any growth/energy going into the suckers is growth/energy that's not going into the tree. Not good.

I'd prune out all the suckers now and then prune off some of the lower branches off the actual tree itself come springtime. Don't over do it.

That's not really a girdling root so I'd leave it alone for now.