Please Help with Flex Design

[Killadoe]

I am a chiller tech and have never done duct design or install. I am in the process of building a house and have a rough layout of the duct design. Can someone tell me what I need to do differently? This is just a rough draft. I will be placing the supply registers near the heat sources. It's also a 4 ton heat pump in the attic of a 2000sqft house in Louisiana.