I'm very sorry your local pet store is just trying to make a sale. I have a few local pet stores like that. It's really rather sad.
I understand that you can't upgrade right now, but this means you're probably going to have to give away some of your fish. The gourami should be the first to go as the tank will never be peaceful with them around. All the pearl gourami and blue gourami (the opaline gourami are just color varients of the blue gourami) should go in separate tanks that are at least 3 feet long. The angelfish should go in another 3-foot tank.
And the clown loach should go in a tank longer than 6 feet!
Gee, those guys get large. I forgot how big they can grow. I once looked into getting them because they were soo cute in the stores tanks, but having the house them in a tank larger than me kinda snapped me back to reality. Loaches Online - My ClownLoach Aquarium
This is a great article about a clown loach setup. Loaches Online - ClownLoach (Chromobotia macracanthus)
There is a picture of an 11 inch clown loach if you scroll down a bit.
Now I know you are thinking: where on earth am I going to find someone to take all these fish? If you can find a local aquarium club many times you can go to a meeting and offer your fish to the members. If you explain your story about bad pet store advice, most people are rather understanding. Returning them to the store is another option, but it depends on the return policies of the store. Sometimes you can say "well they outgrew my tank" and the store will give you credit.
Now onto fish that would be a good fit for your tank. I know you love your clown loach and the good news is there are loaches like him that can fit in your tank! The dwarf loach (click the name to see a picture) is a good fit. Keep them in a group and they will be even more entertaining. http://www.tropicalfishkeeping.com/f...no-fish-96186/
This is a great list of fish that have the potential to fit in your tank. Look through it and since the names are hardly descriptive, click on the shaded names for a picture as well as water parameters and suggested tankmates. The last bit of info we need to know before you begin to stock your tank is how hard your local water is. If you know your water treatment plant you can ask them. Otherwise some people can find it online. It's always best to get fish that do best in your water. Things like hardness can be changed, but it's not easy. Also feel free to ask about anything that you are unsure of. We're here to help!