You seem to de defining things pretty similar to what I do, both ships and missiles/torpedoes.
I often call ASM (anti-ship missiles) for torpedoes and AMM for interceptors and anti-craft (or smaller ships) for missiles. So missiles are often smaller with lower yield and intended to hit fast moving ships. Torpedoes generally trade speed for armour with a high yield warhead to cause shock damage and pierce armour more efficiently. I sometimes also have very fast low range torpedoes that only is for very close combat purposes, perhaps a few hundred thousand kilometres and up to a million maximum.
My ships types say more about their role than size even if frigates tend to be smaller than a destroyer they really don't have to be, especially not between different factions. The frigate are much as you say a ship intended for independent operations, mainly as scouts. Their weapons are mainly to engage other frigates or smaller crafts and they should basically avoid anything else. They can also be used for escort duty.
The destroyer are the main military platform and must be able to perform many roles, pretty much any role that is not performed by a carrier. So they must be able to engage the enemy, protect other ships and scout. Their main role is to be part of naval battle groups and they rarely act alone on any missions. There usually is two types, the slightly larger destroyer leader who is a command and control ship and the regular destroyer. Smaller factions might just have one type of destroyer.
The cruiser is often a controversial type of ship that not many factions will have the resources to build. They must be big enough to be deployed in an independent role and able to perform pretty much any task, including engaging enemy capital warships such as destroyers and even carriers if need be. In essence they are reconnaissance in force type ships. They can operate alone or in cruiser groups or as part of real naval task-groups. Most of my cruiser designs will also have adequate hangar space for either strike crafts and/or utility crafts. They need to have long range, good deployment time, decent speeds and good defensive capabilities, all which is hard to accomplish and still be a potent and efficient design. Cruiser are mainly a way to brag, you show how quite rich and advanced you are to afford such a project.