It's a 9 gallon tank. You are already at your stock limit with what you already have. If the betta dies, don't consider rams for it, that is way too small for them.
I agree you are not over-stocked, right now. What is your filter, I supposse/assume you are over-filtered and planted? I don't follow the 1-inch rule myself, and I kind of despise being told to do so, by many members on these forums, who decide to follow the rule, and stick to the rule without doing further research or knowing specifics about our tanks, or their own tanks. A lot has to do with how well species in a tank are put together, with strong considerations on where in the water column they occupy.I already said I'm not considering rams because the plan is for the betta to not die. I am definitely not overstocked with 6 embers and a betta. Thanks though.