I'm not sure what kind of feedback you are asking for, so I'll offer some general comments. Joist sizing is normally a relatively straight-forward procedure. The key variables, some of which you've mentioned, include span, spacing, species and grade of material, and dead load and live load magnitudes. There are a bunch of other considerations as well: duration of load, moisture and temperature effects, possibility of notching, concentrated load points, etc. Selection of the proper joist size depends on both strength and stiffness considerations. There are lots of design aids available to help you make your member selections. You'll find them in books on home building and remodeling, textbooks, and even in the Yellow Pages under "Engineer, Structural." Good luck with your project.