Not sure what CR you're looking for but I'll throw out a couple things.
Dracolisk from bestiary 1, it's the sample half dragon, could be neat. You can swap dragon color on it for a bit of variety. Half dragon npcs/monsters would be good too if you wanted to do any quick builds of them.
Tatzlwyrm from bestiary 3 is a low level dragon type.
In bestiary 4 Wyvaran is a draconic race that you can add class levels to, or just take the sample one and add hp/atk/ac/etc as needed.
Also Wyverns are always fun. There are a ton of Drakes scattered through most of the bestiaries too if you want to put them with your cultists since Tiamat doesn't always let them command over true dragons.
Korir-Kokembe are river/lake hunters from the inner sea bestiary. It'd be easy enough to rule them ok in salt water and have them wreaking having on the docks area.
Hopefully something here helps you. Most of the dragon types are either true dragons of some sort, linorms or drakes. Very few draconic creatures that I noticed.