It really seems to me that you're mainly not used to a duel scenario, nor do you know how to deal with MAAs.
ZombieRommel wrote: This lead me into games where it felt like my opponent was simply waiting for me to swing so that he could run (or dash) forward during my recovery animation and attack me.
This statement is particularly revealing as there's no reason why you should be swinging if your opponent isn't in range. I'm not sure if it's impatience or what, but if you aren't swinging and creating a situation where your opponent must parry, you are intentionally opening yourself up to attack.
ZombieRommel wrote:And once someone was in my face and attacking, it felt like parrying did not put me at positive frame advantage or even neutral frames. It felt like the parry only blocked damage but did nothing else. Basically I'd have a MAA with an axe right in my face, parry him twice, and go to stab him, but whilst I'm in the stab animation I just get hit again with his axe.
It seems you might not be as familiar with the Messer as you think? It has a terrible stab windup. You shouldn't use a stab after a parry with this weapon.
ZombieRommel wrote:Also, it seems like if you go for a combo attack, you are FORCED to follow through with the whole animation and can no longer cancel it. Is this correct?
You should still be able to feint out of them.