Can i add more fish to my saltwater tank?

I have a 75 Gallon saltwater tank, I have 2 clowns, i yellow tang, 1 leopard wrasse, a yellow goby, cleaning shrimp, emerald crab, and a Saddle Valentini Puffer. One store tells me i can add 6 MORE ( i dont beleive this) and another said i can add 2 more (small) fish. I dont want to over stock but i would love to have a Flame Angelfish and sea urchin. Is this ok? and again how many small fish can i add? do Inverts count?