Are Templates options? if so, what sort of Level adjustment is reasonable? You'd miss out on the HP, but a few grant some serious AC, or DR, or SR, or somesuch. For example, Mineral Warrior from Forgotten Realms Underdark grants +3 natural AC, DR 8/Adamantine, +4 CON, and some other abilities. all for a +1 LA. The +4 CON may make up for the 1 level loss of Hp over a few levels.
What seems to be missing from your build, as mentioned already, is any sort of Spell resistance or other options for avoiding enemy casters. You mentioned magic items not being an option, is this in a low magic/no magic campaign? Why are magic items not an option?