The problem, or at least what I infer the problem to be, is that you're trying on different boots without a solid grasp of what will best suit your foot type. I mean, I have a fairly low-volume foot, too, and quite a wide range of boots fit me, so there might be something else going on.
So, what you need to do is find a really, really good place that sells outdoor boots and has salespeople who know their stuff. Where would that be in Alabama? Well, I'll tell you: I haven't the faintest idea. But you need to find a place like that. Then, you need to spend some time getting your foot carefully measured. Take in the socks you intend to wear, and go later in the day so your foot has swelled to its normal daytime size. Ask for the best shoe-fitter in the store, and wait to see him/her if needs be. Explain your problems and what you have done to solve them. Then, make sure that you know your "true" size on both feetmany people have feet that differ slightly. Have your arch and overall volume evaluated as well. After that, have the salesperson suggest several shoes. Try them all on, in different sizes, and walk around for a bit.
Once you've found one that seems right, take it home. Don't wear it outside for a whilejust wear it in the house, so you can return it if worse comes to worse. After a few days, if all seems well, you can venture out on some short hikes. Give the boot a little time to break indon't do a 12-miler right out of the box. Do all that, and I think your heel woes can come to an end.
That, or just buy a pair of Cresta Leather Hikers from L.L. Bean ($169; www.llbean.com). They seem to fit just about everyone.