There is a girl that I like, and she seems to like me but has a boyfriend. We are both juniors in high school. She seems to flirt with me, at least more than normal from other boys. We just have gotten off our two week break, and since the break ended things are just not the same

This is what happened to me before our two week break:

1. She always asking questions at the end of her sentences
2. She always has some type of sarcastic remark for me (e.g. "I know I have a tough audience to please")
3. Mimics me and my "mannerisms"
4. Sometimes smiles at me in the hallways when I give a "hello face"
5. Asks me to continue stories if I get interrupted, sometimes
6. I think I have caught her looking at me two or three times, I think.
7. She is always giving "knowing you" comments (e.g. Knowing you, you would do that)
8. Asks me clarification questions about what I was talking about
9. When I visit her at work she always asks what I am doing next and what I will be doing
It should be noted that when she converses with me it is not out of the blue, it is usually when I am talking with someone else that she asks me the questions or mimics me. She does ask questions of other people when they are in conversations, but does not use the sarcasm or mimics them, like she does with me.
At the same time she has a boyfriend. Once when I was visiting her at work, he came in (at the time I did not know they were together) but she, after talking with him for a few minutes asked me some questions in front of him and even added a little sarcasm when I answered she said "do I hear a little sarcasm" with a smile. Right before they started going out she was talking about him with her friends when I was nearby and was giving me a sideways stare.
Weeks later, I asked her for her number and she gave it willingly. When I texted her the first time, it took her a while to respond with "Nothing, just at my boyfriends, you?" and then when I replied to her she never replied. I simply wrote it off as perhaps a dead battery. The second time (about a week later) she didn't have the number saved and asked who I was. I replied and asked her what's up and she replied with "Nothing. You? I told her what I was up to and she said "Wow. You are always doing something. I have to go. Bye." This confuses me because if she like me I would think that she would want the number saved, but maybe she forgot.
She never did mention the boyfriend until right after I got her number and she just said she was hang with him, and then asked me what I was up to by text message. I replied with what I was up to and asked her what she did after school and got no response.
I just can’t tell for sure. She acts so nice all the time with me, but I just can’t tell for sure if she’s asking for more. I did think that maybe she acts this way to everyone else, but as far as I can tell she does this mainly to me.

Now that we have returned from break, she won't talk to me. I think I may have seen her glancing at me once or twice but nothing for sure. Today, she did not say a word to me. She did what she used to do to me (sarcasm, imitation) to someone whom I was talking to.

I probably would be able to let it go but there have been the looks. We have even met gazes twice but I just cannot decide what to do.

Please advise on what to do, I will not see her again after Thursday as it is the last time we will have class together.
Do I get through this week and forget about it,
Visit her at work and see what happens there
Do something else?

Thank you

Hey, you can just ignore this one, After reflecting I have decided to move on. So I guess thanks, even though no one responded it did force me to reflect!!

You did the right thing... firstly she had a boyfriend, then most importantly when a female gives you mixed signals, that means she has low interest level... its best to leave that one alone... Or better yet keep your distance...