Thank god you took that diamond goby out of the 10g. I'm going to be honest and do not take this in a bad way just trying to help.
I would just keep a fire fish and clown. Take the damsel out. The tank is already crowded with the two. Next I would also research and ask questions for you make a purchase. That's the 1# thing noobs do is don't research or ask questions.
Lesson number 2# dont listen to your Lfs advice on what to buy. I know there are alot of great owners here. I do. But your own knowledge is power. You find a reputable Lfs and your set. I mean I worked for a Lfs. We are like sharks we smell blood walk in the door(newbs) and we sell
gotta make a living! That's why I would take the time and check out all of our sponsors because those are all of the best Lfs in so cal