I'm sure it does feel weird to you that he has other "girl" friends and girls are used to competing against each other for a guy's attention.
Keep everything cool with you and him and just be yourself. That's why he likes you so much. Don't change because you feel you need to, to keep him interested in you. He already is.
If you feel like you two should be dating, then talk to him about this.
My main advice to you is to just relax and enjoy being you. That's real and that's what he likes about you.