Horwath
Legend
This is simple mechanical suggestion that removes medium armor(it is just an unwanted b'stard child of light and heavy armor) and adds strength for ALL armors.
Armor name and flavor does not matter. You can name it and design it as you want.
Light armor:
AC = 10 + min STR mod + DEX mod
-10 ft speed and disadvantage on dex based attacks if not enough STR for armor.
Heavy armor:
AC = 14 + min STR mod.
-10 ft speed and disadvantage on dex based attacks if not enough STR for armor.
now you can have 5 light armors. from +1 to +5 bonus(12-20 min STR) and 7 heavy armors from +3 to +9 bonus(8-20 min STR).
Armor name and flavor does not matter. You can name it and design it as you want.
Light armor:
AC = 10 + min STR mod + DEX mod
-10 ft speed and disadvantage on dex based attacks if not enough STR for armor.
Heavy armor:
AC = 14 + min STR mod.
-10 ft speed and disadvantage on dex based attacks if not enough STR for armor.
now you can have 5 light armors. from +1 to +5 bonus(12-20 min STR) and 7 heavy armors from +3 to +9 bonus(8-20 min STR).