Is your tank planted. If not watch that your nitrates don't go any higher or even better yet to a PWC now to start lowering them.
"I would get at least two more tetras as they like to be in schools."
That's what I thought, but we were going slow to avoid overwhelming the tank. How many more tetras could I safely add before the tank is overstocked? I want them to be happy, but I also don't want the tank to have issues.