Okay, read this post and take into consideration the complexity of this solution.
You need to do this:
1.) Tell her that you're not going to practice with your band for a week. You're going to check her reaction on this. If she is excited then you'll know that she truly is mad that you're with your band too much. If she doesn't care, then there may be something deeper that you need to fix. Don't think about how badly you want to practice. She doesn't care and I don't care. Be selfless. You could be the most whipped person in the world and she could be your master for all I care. Give just one hint at giving something that you love up and really stick to it. If she asks why tell her that it's been kinda boring lately and you want to spend a little more time with her and homework. Once again, I don't care if you have all the time in the world for her and homework. Lying is important to test her reaction and test the relationship during this week.
2.) Set a date to have a formal date where you dress up and eat dinner at a semi-fancy restaurant. I'd suggest Chili's or Applebee's. The date should be near the end of the week that you promised her that you wouldn't practice with your band. Friday or Saturday is best. You need to set the date on Monday. (Tomorrow!) I'll explain why later.
3.) Purposely do not hang out with her one day that you are available to. If she asks you if you want to or if you want to, then don't! This is really important. One thing she might be having an issue with is that you might be being 'too clingy.' Girls are weird and some get annoyed of stupid stuff like that and they keep the feeling balled up inside and when you want to do something as simple as holding hands, they decide not to because of the extra anger. Not only will not seeing her give her time to reflect back on the relationship and clear herself of any worries, but also it'll give you a chance to just be yourself for a day without worrying about her which also could indirectly help the relationship.
4.) It is important to tell her that you're anticipating the date at least once a day. You need to not only tell her that you're excited to spend some good time with her, but also to remind her that she's going to be spending time with you. Try to tell her whenever you guys are just walking somewhere and she isn't thinking about it. If she looks sad, that's a good time to say it with a grin on your face for comfort.
5.) On the phone, or in person, when you nor her are busy, confront her. Don't be rude, but basically say, "I need to ask you something important." Then just ask these three things in order. Allow her to explain herself if she needs to. Don't rush through the questions but you need to get to them eventually in the conversation. 'Do you think that I am trying to spend too much time with you? What has been bothering you so much lately?' You may or may not have an understanding of the answers before you ask, but these are important to ask anyways because it shows that you are observing the situation and you want to know her viewpoints of it. Basically, it shows that you see an issue and you care about the outcome. If she says that you are trying too hard to spend time with her, don't take it personally. She hasn't openned up all of the way or she's closed up some. That'll open up later on once she gets comfortable with you again. Explain how you can be less aggressive with the situation, too. Then, tell her that anytime she has feelings like that, that she needs to tell you and she can't have the feelings bottled up. If she tells you yes, then say, "Is that why you've been having some really bad days lately?" or something like that. She may say yes but she may say no. If she says no, that you're not intruding in her time, then just be fine with it. The third question you need to ask her after all of this situation is passed or settled, is, 'Do you want us to be together for a while?' She may say yes or no. The answer really doesn't matter because whatever issues you pull from this conversation, you can fix and she'll want to be with you for another 5 months, at least, if you can fix them.

You need to start this conversation on a Wednesday if you're going to have your date on a Friday or have the conversation on Thursday if you're having the date on Saturday. Trust me on this, you need to confront her, get some info, let her realize how she feels, and let her cool down. Ever had a situation where you thought something in your head and it sounded really good, but then you said it and regretted it because you thought it sounded dumb? That's what happens a lot with girls and the stupid things they have called emotions.
6.) Friday morning, you need to randomly do something really nice for her. It's not really my judgment to say what she'd like to receive. Hopefully, you'll know of something that she wants or some kind of gift she likes getting.Maybe get her a CD from one of those gay bands she likes. (This step does not require you to buy her something.)
7.) Like I said earlier, you need to talk about how excited you are about the date you both are going to have everyday. Likewise, you need to try to sneak in some little subliminal messages to her. Whenever you're talking and you can, try to fit in memories of something you guys did. (It needs to be some kind of date you both did or you did with a few of your/her friends.) If you guys went to a theme park and you're talking about roller coasters, be like, "Yeah, remember that time we went to Six Flags?" You need to fit this into at least one conversation a day and at least once during the week, you need to fit it into a conversation that you are having with her and others. (That'll work even better if she's having a conversation with her friends and you jump in.)
I thought about this for a good while before posting and it took me a while to post but if you follow this precisely, you'll win. Believe me, I'm taking some psychology courses!