re: Tell me everything I did wrong with my seafood gumbo (stock & roux quetions)

You need more shrimp shells than you had to make a decent stock. Will your seafood folks save shells for you? If so, call them and ask them to saved the shells and just toss them in a bag in their freezer.

You could add gumbo crabs to the stock if you can find them, but don't buy the Chinese ones. I prefer not to use crab shells. Makes it too sweet for my taste.

There are a few other "base" options to shore up your stock. You could order or buy, if you can find one, a good shrimp base, but watch the salt if you do that. You can also try the "more than gourmet" brand of seafood stock. No salt, so no worries. I think it works better for things with crawfish, but it's better than a weak shrimp stock. Reduce the stock until you get the flavor you want. You don't need onions, carrots and the like in the shrimp stock for this. You can also roast your shells a bit before making your stock for a deeper flavor.

Some folks use dried shrimp to shore up a shrimp gumbo. I have never used them, but someone might come along and tell you how that works. They are stinky little things.

You have too much stock to roux as others have said. Try 1/2 cup to 1/2 cup flour and oil to 7-10 cups liquid, depending on the texture you want.

A few red peppers, very few, is okay, but they're taste sweeter to me than the green. Veggies definitely too chunky for my taste.

Go darker on your roux whatever way you choose to make it. I don't deal with the microwave for roux, so I have no idea how that works. Couldn't make a roux big enough for my use in the microwave. I'd be microwaving all day long.

If you have some leftovers, make another roux and add it and see what you think. May as well play around with what you have. Just take the shrimp out and add them back right before serving, so they don't overcook.

For chicken and sausage gumbo, use Paul Prudhomme's recipe as a guide for your measurements.
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