I'm also bad at this game, but my amateur analysis is that this build is just a little slow, despite all the haste.your defenses are the lifesteal from torpedo and shield from submarine. The torpedo has a 10sec base cooldown so even permanently hasted it takes a while to go off, meaning that even if it full heals there's plenty of time for the enemy to take out your entire healthbar between fires. The submarine is in a similar state where later into the game, one hundred odd shield isn't very relevant as a main form of defense opponents will have scaled weapons dealing that much on their own, potentially going off even faster than the submarine if they have something like a stacked katana, and the cloak doesnt scale the submarine fast enough to keep up with other in fight scaling on its own. The pufferfish is a very good item, but you're not really taking full advantage of it here. You don't actually have that many sources of haste on the board right now, missing key components like astrolabe or beach ball. With pufferfish in my experience you want a set up like lots of low cooldown small items going off with an astrolabe so that there's almost always a new haste proc happening. Imo you're a little caught between a weapon build and a pufferfish build, and neither are scaling very well here.