My instinct was right. She's not interested.
I asked her to hang out. She used two different excuses: she had to meet with her mother and had a lot of study to do, and she said "maybe next time." I said "ok, next time," and she said "sure." I asked her on the same day, so it was understandable if she didn't expect it and already had a plan with her mother or whatever.
Few days later (today), I asked her again, but this time it was a day in advanced. This time she said she had to work. Surprisingly, I asked her to hang out at about the same time and same day as the last time that we met in school, but this week she had to work?
I believe it's time to next her.