What sorts of ships do the fleets that are likely to oppose your have? For what sorts of missions do you intend your fleet? What patterns of maritime trade are you involved in? Do you have colonies, protectorates, or other overseas responsibilities? Do you have allies?
At the very least, you might want specialised air-defense/anti-missile frigates or destroyers, as well as specialised anti-submarine ones (and perhaps a general-purpose class too), rather than just a single unspecialised class, to escort your other shipping.
Minelayers, minesweepers/minehunters, coastal patrol boats & & river patrol boats), various classes of ship for use in amphibious operations?
To answer your questions here:
What sorts of ships do the fleets that are likely to oppose your have?
-I don't know, factbooks and such are not completed in some areas and I haven't had a chance to get a complete listing for some. In addition, the nation was in some heavy isolation, so it went mostly general roles, not focusing on what it needed to fight nation-wise.
For what sorts of missions do you intend your fleet?
-I'm following the Near/Far Seas doctrine China has developed, as I found it quite fitting. Now and during the isolation, they focused on defending the sea before the mainland and trying to have ships a bit further out to protect their trade lanes and to try and meet any attackers before they reach the mainland. Over time, we intend to work on being able to support blue-water/expeditionary missions away from our local area, but thats going to take time.
What patterns of maritime trade are you involved in?
Admittedly, I'm not very well-versed in this. From my reading on China's PLAN and its doctrine, they are focused on Sea lines of communication and trade lines that ensure they get the energy resources, oil and so forth, to their nation. I would imagine that would still be important to my nation, even during its isolation.
Do you have colonies, protectorates, or other overseas responsibilities?
-No, we never got any before the withdrawing into our ourselves, and for the moment, we don't intend to get any since we're not capable of handling it.
Do you have allies?
-Didn't before, do have a few now that we are working with to fix and update the military situation.
The classes of ship I am using are focused on air defense, with upgraded ASW and AShM abilities. The destroyer, the frigate, and then the sub, which has torpedos and then AShM cruise missiles. I do have patrol boats and missile boats for coastal/littoral operations and amphibious ships all set up, and the submarines I have have the capacity to do mine laying, and the supply/repair/hospital ships are set up. I was just looking at the carrier and its escorts and saw a lot of variants, but for PLAN, it was mostly a matter of they had gone through several iterations of destroyer, frigate, etc and hadn't bother to phase them out yet. Which my nation would have. And I know if I get too deep, I'll get really confused if I have to deal with six variants of each class at the start.
*PLAN: People's Liberation Army Navy.