The expertise rating cap for cat druids is 132. Assuming you took two points in Primal Precision for a free 10 expertise then 132 expertise rating from your gear gives you a total of 26 expertise, which is just enough to overcome the 6.5% chance a raid boss has to dodge. (The expertise cap is higher to avoid parries, but cats should only rarely be in a position where they can be parried.)
132 expertise rating is not very much: a lot of our best raid drops have expertise, typically 35 or more expertise rating each. In other words, after four pieces of expertise gear the stat is wasted. I've got too much expertise gear myself. These days I'm relying on a special Pawn scale that values expertise rating at 0 so I can better organize my gear.