I don't see the boiling everything together and how it can get a good flavor.
I usually cook fish sauce in two or three stages - i think it gives a far better flavor.
Also never never never drain the pasta and just leave it. The sauce should be ready before the pasta is drained so it can be immediately mixed with the sauce. It will get sticky and yucky if you leave it without sauce, and if you mix it with oil you'll just make it so the sauce won't stick. And it will be cold anyway!
Here the shrimp are usually left in their shells and you are left to clean them in your dish. I don't much like it because i never figured out a graceful way of shelling them and end up with both hands in my pasta sauce and my clothes completely sprayed. But i will admit it does have a certain appeal to see the whole shrimp with its little feet and all.
It's not at all unusual to have a mixture of fish in a pasta dish - spaghetti alla pescatora. But you can choose any single one of the fish below and probably others too.
Finally, there is no reason it has to have tomato (i do prefer it, but it's not easy to get seafood pasta with tomato here, they usually do it without, and if there is tomato, it's very little of it. In any case, dried tomatoes are way too overpowering for seafood. And if you insist on using them, you should soak them a lot in hot water to soften them and get rid of the salty taste.
Here's the procedure i'd use.
Put some oil in a pan. Heat it and then add a bit of smashed garlic and a few flakes of hot pepper if you want it, plus the bivalves - clams, mussels... Then cook at medium high heat till all of them open (or a couple don't, which means they were dead and you have to discard them). Dump this all into a strainer set over a bowl to catch the liqueur and the oil.
Put more oil in pan (you just need to film the bottom)
Again, a little garlic and hot pepper and the other non bivalve fish (shrimp, calamari, etc) and cook over medium high heat till opaque. Dump them also into the strainer and catch the juice.
Reduce the juice in the bowl under the strainer in a pot, adding the wine (definitely not a cup and a half! - maybe half a cup) and let it reduce significantly so it's a bit syrupy. [If you want to make the pasta without tomato, then you'll want to first sautee a few cloves of garlic in the pan with a bit more oil, which carries the flavor, some hot pepper, and then add the wine and reduce to syrup, then add the liqueur of the fish and cook it down till you have a tasty sauce, not too watery but enough to flavor the pasta. With tomato you can reduce it further - see below.]
For sauce with the tomato:
Again a little more oil than before and this time add a few cloves of garlic, some salt and some more pepper flakes, let them cook very slowly till soft BUT NOT BROWN and add tomatoes - and raise the heat and cook rapidly for a couple of minutes.
Add the reduced wine/liqueur and cook a few minutes (not too long - the tomato should taste fresh, not like a ragu!) .
Shut the heat and now put the pasta on to cook (you already have the water boiled, and make sure to use a lot of water and a fistful of salt - most of the salt will remain in the water, so don't wiorry)
Two minutes before the pasta is cooked, put the fish into the sauce and let it cook these couple of minutes, to flavor the sauce and to let the sauce flavor the fish.
Drain the pasta and dump the sauce immediately on it (i drain it and put it back in its pot where there's plenty of room to mix)., Mix it well so it;s all coated.
Serve immediately with the parsley chopped on top (not cooked - that changes its flavor)
Note that the tomato is light, not thick, it's mainly the reduced liqueur and wine with some tomato flavoring.
Try this and tell me how it is.
It is not as hard as it looks.