Rams are fine with discus. if anything id ditch the nerites as they can/will eat the slime coat on the discus. I would get 4 more BNP's, dont get the rummy noses till the cardinals die off, replace them with those.
For the tank size, type of fish and filtration system with your PWC schedule you will be fine.
I got over 50 tetras, 20 discus,24 or so cories, 10 bnp's 4 yo-yo's 4 sae's in the 210. I have the filtration and water change schedule that permits it.
The fish there have small bioloads minus the discus which arent heavy but arent light on the system either.