Your loach will outgrow that tank because to be happy he'll need at least 2 more friends. I was given a loach with my 29g so I took him to an lfs and got some store credit towards other fish. Call them first to see if it's okay. Privately owned pet stores are more likely to take your fish than a petsmart or petco-type store. A 29 or 30g would never be big enough for that they grow too big. So I think that you're making the best decision to give him an opportunity at a more suitable environment.
Best case scenario, your otos should be in a group of 3 minimum as they also school. But your tank doesn't have enough room right now. Don't forget that your oto needs a little piece of driftwood to rasp on and it will last him forever. The wood provides fiber to help his stomach digest properly.
Glass Cats should be in a group of 3 - 4 minimum so I would say that you were doing okay. They'd be happy in a large group too, but so would all schooling fish. They would probably feel more secure with plants. I don't know if you have any plants in your tank but that might help them not feel so exposed in a wide open tank.
When you stock your tank you need to consider the adult size of the fish, not the size they are now. So taking that into consideration, you are already maxed out, even if you rehome the loach.
Be sure to keep up with frequent water changes of about 20 - 25% 2 times per week until you can rehome the loach. You don't want the ammonia and nitrates to build up to levels that will make your pets immune systems weak and then have anyone get sick and even die. Frequent water changes will help them stay healthy while the system is overloaded.
You can make up your own tank stocking limit sheet to figure out what you have currently. I've created this one as an example.
Breed -> Size x Qty = Inches of fish
Mollies -> 4" x 2 = 8" of fish (depends on the type of Molly. Blacks are 3", Silver Lyrtails are 4", & wild are 4.7")
Oto -> 1.5" x 1 = 1.5" of fish
Glass Cats -> 4" x 3 = 12" of fish Clown Loach
-> 13.8" x 1 = 13.8" of fish
Blue Rams -> 2" x 2 = 4" of fish
Bumblebee Goby -> 1.8" x 2 = 3.6 of fish
Add up your inches of fish and you get:
Total inches of fish per gallon = 42.9
Total without the Loach = 29.1
You'll be in good shape without the loach and I wouldn't add another fish at this point. I like you selection of fish. Have fun!