Well, you may be lucky to find female dwarf gouramis these days…be careful they are female. & I would get 8-10 corys of any of the same species (pandas are cute!), they're more fun & happier in a larger group, get more than 4, 6 is a minimum, get 8.
Your 16-20 mixed tetras & rasboras seems like a lot...especially if you go with 2 or 3 gouramis. I'd say go with 1 species of either 10-12 rasboras OR tetras OR skip the gouramis. Keep in mind lfs fish are often juvenile. & also, it seems the last several years dwarf gouramis are not as healthy as 1 would like. They are prone to an untreatable virus. That's part of why I suggested honey gouramis, but they can get the irridovirus (?sp?) too.
You seem to have a fairly good grip on this stocking thing but, like many, want more fish than optimal for a happy tank. Think hard...you can always add fish eventually...