What do you mean that you lose your potions? That shouldn't happen, do you really mean that you had potions at the end of the week and next they're gone from your inventory? Or do you mean that your characters sometimes use your potions when not needed?
I'm sorry that you don't like the way I've done the combat and not giving you the option to do things, I actually had an idea how to improve the gameplay by introducing combo mechanics to some moves, such as the Spray Milk that Rinoa likes to use, so that she could follow that up with another move without "wasting turn" just to debuff an enemy.
Did you really have problems with durability already so early into the game? I may have to look into increasing the durability values, if it's already this early into the game a problem.
EDIT: I found out what you were talking about the items, they're not gone. This is an engine problem when accessing these menus when you have no actors at all in the party, I will hide these menus in future when you have no mercenaries as a workaround but rest assured, your items and equipment are not gone they just don't display correctly without any actors, due to the way MZ's Scene access (via mouse/keyboard) is gated by menu state (Scene_Menu.prototype.commandItem), which checks for this._actor or $gameParty.menuActor()— both fail if the party is empty.