okay. so i know its really confusing..and everyone show different signs for liking people. but the main thing im going to get into here..is that you're asking why she doesnt ask you out. now, i know its the 21st century, and girls ask guys out all the time. but if you're nervous, she probably will be too. i liked this guy for a long time and it ended up that he liked me. we went for 2 years without asking eachother out bc we were too nervous..finally at a dance he asked me. you see, asking some1 out, especially in h.s. is rly nerve-wracking. if they say no, you have to see them almost every day for the rest of hs. maybe going to a dance or party will help where you're in a more romantic environment..start out with a dance or something. if you think she likes you, go for it.
good luck. :)