I like her but im scared. What should i do? What should i say to her?

So i like this girl named Jennifer, we met in 6th grade and got really close in the Summer of '09. I started to like her during that summer but told her how i felt durin winter break. She told me that she kinda liked me but wasn't sure, blah blah blahh. So this year we go 2 the same school because we didnt last year and wen i first got to the school we wud p by each other like we were strangers and it killed me. But now we talk when i see her while going to my cles i hug her and we mess around, she texts me in the morning sometimes. So as the time went by, my feelings for her started to come back and grow. I told my friend Natasha and she said that im in love with her but i dont think so and she said that i shud tell Jen how i feel and that i wanna go out with her and flirt with her so she can fall for me but i cant. I dont wanna make things awkward between us like it was last time. Also, today i skipped to my friend Natasha's 4th hour (the one i told u about that wants me to tell Jennifer how i feel) and Jenny is in her cl. So Jennifer saw me and messed with me and stuff and she invited me to hangout with her at the movies with her bf, her cousin and her bf and other people. But at the last minutes she cancelled. But later on today, I talked to my friend Amy after we got off the bus and she told me how on like Monday or Tuesday this week Jen texted her while she was sick and said "Djaida still likes me =O" but Amy wasn't feeling well so she didn't reply back. So idk if she likes me or what like im confused.....So idk wat to do. I like her a lot and wanna go out with her but idk how i should flirt with her to make her like me like my friend Natasha told me i should do. Please help me.....Btw she got a bf like 4 days ago but yes im bi and so is she.