Should i move on or should i stay with the girls?

i keep going out with my sister, i hang out with her and her girl mates, i really like hang out like in clubs with the girls, and she says because she wants me to find friends possible a girl friend but i getting a felling there using me and im not really speaking much to them because its my sisters mates, and i also like one of her mates but she has a man. should i still hang with them or do i really need to find friends by my self?