Are these pictures "professional" looking enough that I could call myself a professional and start my own business?
I want to break apart these two questions:
1) Are these pictures "professional" looking enough that I could... call myself a professional?
2) Are these pictures "professional" looking enough that I could... start my own business?
For your first question, I say not yet. Someone here said, "Practice, practice, practice." I say you need instruction, instruction, instruction. Learn lighting and posing. These two go hand-in-hand. Even if your style will not be
creating poses and light, knowledge of them will allow you to
recognize good existing light and direct your subjects so they move into good poses.
Start you own business now? Sure! You seem to have a good, natural sense of composition and your technical is adequate. There is a market for what you're doing now... a good one. I suspect there are MANY more photographers of your caliber than those who can call themselves pros. Remember... being a
pro is all about proficiency and not merely getting paid.
Good luck!
-Pete