Just to be clear, you already have the otos, rams, galaxy rasboras, harlequins and sparking gourami, and the rest are fish you don't have but would like?
Rams - if you do get a male, there is a good chance he will pair up with one of the females and make life difficult for the 'spare' female. Be prepared to rehome one of the females if this happens. If course the male might not like either of the females or they might both take a dislike to him.
To be honest, the first thing I'd do is get more of the galaxies and harlequins. Galaxies are shy little fish and do much better with larger numbers. So a total of 10 galaxies and 6 harlequins. That would put you at 58% stocked.
Of the 'wish list' fish -
Pygmy cories are another small fish that does better in a big group, so you'd need at least 6 of those. They also need smooth gravel, or preferably sand. The rams would also do better on sand. But with rams in the tank, there could be problems. If you get a male and female that breed, they will chase everything away from their eggs. Cories have no concept of territory. They will keep wandering back towards the rams eggs and could very well end up being bitten.
Ember tetras - fine, and 6 should be enough of them.
Fiveband barbs should be OK, but more than 4. With shoaling fish,, 6 is the absolute minimum.
Dwarf rainbows - again at least 6. I had these for a while in my 180 litre tank that is 107cm long. I felt they were too overactive even for that length tank. I assume your 110 litre tank is shorter than that? (I gave mine away as they were just so exhausting to watch)
Golden pencilfish - biggish fish but sedate. At least 6 would be fine. (I have 12 of them)
Dwarf gourami - make sure the tank it comes from has no sickly looking or dead gouramis in there. So many dg's arrive at the shop already infected with the incurable dwarf gourami iridovirus.
If you were to get all those fish, your tank would be 162% stocked.
If this was my tank, I would forget the barbs. They are the same colour as the harlequins. And the rainbowfish (having had them already and finding how hyperactive they are). That takes you down to 107% which, while overstocked, would be do-able.
I'd probably also forget the cories simply because of the rams.
There are two ways to stock a tank. The minimum numbers of lots of species, or lots of a few species. I fall into the second group.
In my 180 litre I have 13 cherry barbs, 12 pencilfish, 3 apistos, 3 loaches (was 4 but one died shortly after I got them) 4 otos, and 6 stiphodons. The 2 ember tetras and 4 microdevarios are the last of shoals - I won't be replacing them. And yes I am overstocked!