Well, Zebra Danios get to 2 inches long (that's what the glofish were before they got the jellyfish glow stuff) and you have 3 of them, making 6 inches.
Then your betta at 2.5 inches brings you to 8.5 inches.
Then the mystery snail I've heard needs needs 2 gallons of water to be healthy 'cause they poo so much so that's 2 more inches bringing you to 10.5 inches.
I'd say you're stocked as is!
Also, I agree with clinton. Many other fish will nip at betta fins because they're long and flowing. As a matter of fact, I'd watch the glofish for that as well. I had danios in a tank with some cory cats once and they nipped one of the cat's tails down to nothingness before I'd realized it.
And yes, mollies are nippers.
Anywho, I'd stick with the stock you have now!
