Welcome to TFF.
Increasing the neons is a good idea. And as other members noted, you definitely need more cories. Corydoras are shoaling fish requiring a group of their own to be less stressed, and the more the better, subject to the tank limitations obviously. The same species, or you can mix them. All tetras are also shoaling, and 10 neons is a good number.
The single Bristlenose is fine; just make sure there is at least one chunk of real wood, as these fish must graze wood; they do not "eat" it as food, but they do consume what they graze and it is necessary for a healthy interior.
As for the gourami, this species (Trichogaster labiosa) is quite peaceful and a small group would work. However, males are territorial (like all gourami species) and it might be best to leave the present fish on his/her own.
You have lots of options for additional species. Other peaceful tetras (some are, some are not and will nip fins on gourami), rasboras (also shoaling species) would be OK.
