
Your 3/4 tones have certainly gotten darker - but is that a bad thing? How much is enough? How much should you see? It can actually be tough to say. Lighten up too much and you give up your only real meaty shadows. In any case, a more gentle bit of curve work could spare the 3/4's and beef up the mids as you like.
Regardless, it is very tough to show good highlight and shadow detail in an image and still maintain pleasant contrast. Most images don't - renders and photographs both - so finding good reference can be hard.
Also - it's very easy to oversaturate a shot when adjusting contrast. You need to separate colour contrast from tonal contrast and control both to get the best result. I'd avoid using Levels and brightness/contrast type tools. Use curves if you aren't already.
Anyway, as I said - whatever works for you

b