Welcome to the forum!!
I agree with Jaysee, especially about the dwarf gourami. I have a male/female pair in a pond that's a pretty decent size, and even with all that space they still nip and chase each other. In a 20 gallon, it's very possible for some serious injuries.
Tiger barbs also get quite large and boisterous, and I wouldn't generally consider them good tank mates for gourami.
As for the kuhli loaches, what type of substrate do you have? Gravel or sand?
What are the parameters for your tank in regards to gh, kh, ph?
AqAdvisor is a good tool, but it doesn't always take into consideration all of the aspects, so it's not great to fully rely on it. When I use it, generally what I do is plug in the fish and do separate research on each fish, look at pictures/videos/journals and compile the best possible stock I can. This is truly key for successful fish keeping.