Is it right the way i treat this chick?

there is a 15 eyar old girl that likes me and she is pretty hot i'm 18 btw well i have sex with her she is goin crazy right now thinkin i got her pregnant i told her to chill the f*ck out or i won't mess wiht her anymore she started crying. she is a shy girl with me in person but on fb or txt she is fine. well yesterday we had sex thats what she is frekain about and i think i was a lil too mean to her when we were havin sex. i am the biggest she ever had she told me that and she doesn't like people pickin her up and i did i picked her off the ground and had sex with her and when i was fingering her she started bleedin she has a fear of blood i didn't stop bc i told her i wasn't going to stop unless she asked me to and her being shy i feel i kinda used her shyness on her to get away with it. she says it was amazing for her her last guy didn't know how to work it at all he didn't touch her much or anything and i was slappin her @$$ shuold i cool it on what i do with her. age don't matter to me unless she has a proble with the age differnce and she has said she doesn't. should i treat her a lil nicer? she said she enjoyed herself and she doesn't want me gettin into trouble and she would never tell on me for it so. she likes me more then a frined i only lust her i like her as a friend but i lust her she is like a booty call for me she is always askin for me to come see her and have sex wiht her but i don't know if its cool what i'm doin.