How to know if she likes me

I am currently 17 years old. recently i met this girl at a party through my brother. I've known who she is for several years but never really "met" her, on account of me being shy and assuming she was well out of my league. Anyways, she is really cool and pretty. a few days later i texted my brother and asked him if he thought i should press the situation with her or just let it slide. he said she told him that she thought i was really cool and hot, but i just didn't talk much. he suggested i text her and see how things went.
Two days later i manned up and did just that. it went alright, and she seemed somewhat interested in carrying on a conversation. we talked for twenty minutes or so before my phone died. the next day i was a little weary of texting her again as i didn't want to be annoying if she wasn't interested. much to my surprise, she texted me first. this reassured me quite a bit, and i asked her to hang out, as i was with some of my friends, and she with one of hers. she said she would but she had to get up early the next day but that she would next time.
Over the next couple of days i continued to text her and things went pretty well. We weren't having one sided conversations and she seemed interested in talking.
The problem here is that i have begun to like this girl and I can't tell if she likes me or is just being polite and friendly. I don't know how to convey this to her without pushing her away or entering into the "friend zone." Normally i would ask my brother, as he is extremely helpful, he would probably set something up that both her and I would be at, but he is in military training right now and won't be in contact with me for 4 weeks.
Another question I have is, considering the fact that she is currently on vacation for a few days with some friends, should i text her or wait and see if she texts me, so as not to potentially disturb her?

any help is appreciated, thanks in advance

Ok! It sounds to me like this girl is totally in to you. She text you first which is usually a good sign (she wouldn't text first if she was just being polite)

I would not text her while she is on holiday with her friends as she may be busy with all her friends.

Do you know exactly when she gets back? I would text her the day she gets back and ask her about her holiday. Then once you have started talking to her again I would ask her if she wants to go to a movie or something.

Hope this helps