Tuna and Shrimp Pasta

I am not usually a fan of canned tuna, if fact I don't like it. I was reluctant to try this. The creaminess of the Alfredo sauce and the addition of the salad shrimp made this the best tuna dish I have ever had.
Tuna and shrimp casserole

16 oz. box Rotini
1 onion (diced)
2 cans tuna (drained)
1 small bag of Salad shrimp
1 jar Alfredo sauce
2 Tablespoons Oregano
2 Tablespoons Garlic
salt and pepper to taste
1 cup cheddar cheese (shredded)
8 oz. frozen pea/ carrot mix

Boil noodles per instructions on box. While making pasta, Sweat onion in a 2 quart sauce pan. Add all other ingredients to the sauce pot and simmer on low until pasta is done. Drain pasta and place back into kettle, add sauce and stir well.