What kind of frogs (African Dwarf or African Clawed? What color are they and how big?)? What kind of catfish?
Your tank is unfortunately over-stocked which is probably making it difficult to maintain good water quality
. You may need to return some of the animals. The water change schedule seems good, I think it's just hard to keep up with such a heavy bio-load in a tiny aquarium.
To save your current animals you can do a third water change weekly to keep the water clean (you won't have to do this forever, just until you fix the problem). The gourami may not make it (the dwarf guys are pretty sensitive now and I wouldn't recommend them at all) but it should help prevent any more deaths.
If it was my tank, I'd return the gourami and catfish. Possibly the frogs depending on species and how well they're eating (they can be tricky to maintain in community tanks). If the frogs were returned, I'd then get a couple more tetras to have a school and then eventually add another animal...perhaps a single betta, a few pygmy cory cats, a single bristlenose pleco, etc. And that'd basically be the max for a 10-gallon, they don't have much room. Beginners are always better off with tanks of at least 29-gallons IMO. A 10-gallon has little room for error as you're finding out.
Good luck and welcome to the forum.