Great post, there is also a thing called a supercooled liquid, and an amorphous solid. You can consider those also as different states for a material. I wrote about glass, an amorphous solid in a previous article. Check it out if you like!:
https://steemit.com/science/@awesomebiology/is-glass-really-a-solid-material-or-liquid-or-neither
Supercooled liquids and amorphous solids are either combinations or variations of the states of matter rather than them being their own state. As for plasma, or what I am going to talk about in Part 2 (Bose-Einstein Condensate) - they are too different to be described by the states available so are their own.
Thanks for your comment and will give your post a read! :)