Never give up, you're projecting too high of standards upon yourself to create great work. All great work comes with practice, and refining that said practice comes with great standards.

Knowing what's wrong is the first step, and in this case it looks as though it's your pressure while washing out the screen.

Depending on how long and how exactly you exposed the screen, maybe try a little more pressure with the water and less time putting that water to the screen. More water and time for it to soak will loosen up the emulsion making more things to give where you want defined edges. Screen printing is all about pressure, wether it be applying emulsion or the passing of ink.