Whats the next move?

i have been single for a year and half now, not by force but by choice, during this period i have had countless meaning sexual relatioship and currently have one. while that is fun and all i miss having a girlfriend. my problem is, i am 21 and due to the fact that i always chill with people older then me that i find women around my age to be immature. all my serious girlfriends have been older then me and of course they all ended badly because i either lied about my age or because we are in different chapters of our life. i met a girl about a week ago and she is actually 20!!! we have so much in common and she just so happen to talk and act so mature. Writes poetry, great sense of style, very comfortable with herself but there is a glitch, she has a boyfriend. we have known each other for a week, hung out 4 times. her bf doesnt live in the same state as her, though she has mentioned him, she has made herself available whenever i asked her to hang out, calls and text me. but i can sense base on her body gesture that she is shielding herself in case i make a move, havent kissed in a week!!! thats new to me especially if i am spending so much time with a girl, not to brag... whats the next move?i know actions speak louder then words but the way she be distant and stufff, i cant find room to make a move, do i wait or do i just come out and tell her how i feel and ask her how she feels bout me, i know that is the wrong way to go because it might scare her away but im at an impasse right now...