Depending on your skimmer, i'd say you are fine so far and should be able to add a few more fish without a problem. I have a asm g3 and have been at zero nitrates since i added the fish even though i feed pretty heavy.
If you have enough live rock and pods, the mandarin shouldnt be a problem. Not sure if you can have 2 in a 180g but i belive you could without them fighting if you have enough pods.
I'm the opposite as you,lol. If it wasn't for the wifey, i would be fine not even having any fish in the tank. I'm only interested in the corals for the most part, she only cares about the fish. She pretty much thinks corals are just expensive rocks
