Am I overstocked?

[bleevin]

Hi,

I've got a 120 gallon tank with aprox 130lbs of live rock. I'm trying for a mixed reef tank. I was wondering if I'm overstocked? I currently have the following fish.

2 false percs
3 Anthia - not sure which ones they came with the tank
1 shrimp goby
1 tiger shrimp
1 yasha hasha
1 yellow tang
1 female blue throat trigger
1 red sea sail fin tang
1 coral beauty
2 cleaner shrimp
1 tiger tail sea cucumber
1 tuxedo urchin
number of snails

I've also got small colonies of digi, acropora, millies, crocea clam, green bubble tip, torches, hammer.

If I'm not overstocked how many more fish can I add and which types? I would like to add a fish that spends most of it's time swimming in the water column. I was hoping to add a juv and watch it grow also..

I would like to add the following...

1. Some kind of sand sifting goby...preferably one that eats hair algea
2. Another tang? Powder brown, or male blue throat trigger or possibly some kind of angel? Any suggestions for other species of fish?