I attracted a girl about 4 months ago. Since then, I've seen around once every other week for about 3 months. Mostly, I took her to parties and hung with her and 1-2 of her friends. Since the start, she's been pretty flaky. She shows interest and then flakes almost 1/2 the time.

I took her on a first, legit date around a month ago right before break. It went well, and I got the impressing she was pretty into me. She went out of her way to actively ensure the date was a success. I didn't see her again since then because we were both at home over break.

I'd been initiating text messages with her almost exclusively, so over break I stopped texting her. After this, she initiated a series of text indicating she wanted to make sure we hung out more after break.

About a week ago (when I knew she was back in town), I sent her a text asking her if she was back in town. No response. Thursday, she sent me a text asking what was up - we fluffed for a bit, and I invited her over for Friday. She said she couldn't make it Friday but would be down for another time that weekend. Friday, I texted her asking if she'd be down to hang out Saturday. No response. Saturday, I texted her once more in the afternoon to see if she would be down to hang out that night. No response again. I haven't contacted her since then.

Should I take this as a sign of disinterest? How should I respond when/if she texts me next?

Are you sure you attracted her? It sounds like you're just a low-priority friend. Especially since you're never alone with her. I think you should try backing off completely for a month or two so your relationship resets, and then try again. Tell her you're working through some things so she can expect a transformed man and when you're ready to see her again, be a guy she can be sexually attracted to. Having a plan independent of her texting you or not is a good idea. While you're doing this, maybe she'll miss you and take the initiative to see you, in which case you should pounce.

I am alone with her every time she comes over for a reasonable amount of time. I isolate her from her friends. I've hooked up with her several times, but I haven't had sex with her.

When I invite her over to hang out, it's usually me inviting only her over, her accepting, and then her asking if she can bring a friend along.

Lets assume the best case scenario and she doesn't trust herself with you is why she drags friends along. Show her you mean business by not letting her bring a friend next time. If she can't be with you without a chaperone, that's a problem. But that's down the road. If she only agrees to see you every other week, I doubt she's that into you and is using you as a last resort when there's not other guys to hook up with/nothing more interesting going on. If she was into you, you'd have problems getting away from her. Since she won't reply to you at ALL now, you have to mix it up and put something on the table that is more exciting than what your competition is offering. And why not call her instead next time to make it really exciting. Even if you just get voicemail, fucking sell it like it's the biggest thing she'll ever miss. If that doesn't get her attention, I'd say go with my first scheme.