What type of gourami do you have? You should be able to add a pair of females with the tank that size; make sure there are several hiding spots in case they have some lovers spats. Having 1 or 3(+) gouramis is better than 2 usually, because then you don't have a single dominant fish constantly harassing one other - he has to spread out his attention and it gives both subordinate fish a chance to have some peace. As far as I know, they don't form mated pairs like some other fish do, although I could be wrong about that.
I wouldn't add any dwarf gouramis if the one you already have is a bigger type (blue / gold / opaline / platinum or pearl), since dwarfs have more passive temperaments and would be bullied.
You also have more room to play with and more stocking space if the tank is long, rather than high - gives more swimming space for most species.