Okay then. Your bottom feeding sucker really looks like an otocinclus catfish also known just as otos. Are they more often on the side and on your plants? Mind never were on the bottom much. And then yes a kuhli loach.
I would up your kuhli loaches to six (that is the eel thing). They like to be in groups and these will be your bottom scavengers.
If I am right and you have otos then be aware that these guys need alga; without they can starve. That is why many people wait to add these to a more mature tank. You can try algae wafers and moisten them and stick them to the side of the glass if you don't have enough algae. I would say up these to six as well but don't do it until yours are more than 6 months old.
You are missing a schooling fish like a small tetra, neons, rummy nose or flame tetras for example. Get a school of 8-10 of the same species. Then you could do a male/female or male/2 female of dwarf gourami to spice things up.
Good luck. Make certain you have a good liquid based test kit as you are a waterkeeper as much as you are a fishkeeper.