help understanding "clues" from a girl

hi,
so this past week i got to meet one of my friend's sister that i never knew before and my heart just fall right to the ground. i couldn't take my eyes off of her. she was here for a week.
i think we had something going on between us, but I'm not so sure so i need some help in understanding them.
first day she came, we drank beer, talked, she was sitting next to me showing me pictures of her in high school, in a bikini and she told me "i wish i had more picture like these to show you".

every time we were in a room together we would just look at each other, sometimes smile, but usually we would look at each other because someone else said something and it was like more of a comment exchange face between us.(this happened all the time, but no so much in her last days here.)

i heard her talking to my friend (her brother) telling him that she really likes me, and he told her, that she says it about everyone of his friends, and she said "no, he's different". (that was in the 2nd day she arrived here)

she was "protecting" me, defending me when her brother would make fun of me (just kidding fun) and she would answer instead of me sort of a thing... (that was mostly all the time but especially in her last night)

she told me that i could come and stay with her a couple of times, "if you ever happen to be in...", "its not a big deal to get a ticket online".. (she said i can come and stay with her 2 days before she went back home)

a day before she left she told me again, you can come stay with me, and we went to the hospital (her mom was sick) and i saw her crying and feeling bad and i was so sure it had something to do with me too, i cannot explain why she wanted me to come with her, but my friend (her brother) isn't the best around and she knows it so i felt like she was crying some because of me, but its hard to say because her mom was in the hospital..
and so i sent her a text message saying "when can we talk?" and then she saw it and we went outside to talk, i told her that i know i am in a bad place right now, and that i would like to moved out with her, i asked her, what do i say to her family? and blah blah, well anyways when i told her that i felt like a decrease in "what we had", she told me that she would have to talk to her boyfriend (she is in the navy, so is her boyfriend) and i felt like she wasn't really expecting me to say that, which was kind of weird because i swear she told me that i could come stay with her like 3 times in a row.

when she left and we said goodbyes, it was just plain and simple "nice to meet you" and that's it. i think i could tell a little bit that she was nervous/in a hurry/upset, i think its because she had to leave her mom, and family and she was running a little late too.

i still cannot take her off of my mind and it killing me, i know i want to be with her, i am pretty sure there was a "connection" between us.
the whole time she was here i try to show her how much i care for her, and i think she noticed it. and i got the same from her.
i don't know what is her relationship with her boyfriend.
I'm 23, she is 25.
please, was i right about her feeling for me? did i understand the "clues" correct?
what should be my next move?

i want to send her an email, asking how her flight was, telling her more about myself, talking about her visit, i wont write anything about relationship, would that be a good idea?
should i talk to her brother and sister about that? ask them what they think about us?

There is no harm in a friendly email, just becareful she has a boyfriend already remember.
So just stay friendly. As for going to stay with her i wouldn't do that, untill your sure what the situation is between you both.
Im not sure the BF would be impressed with you going to stay with her friends or not.

thank you for the replay,
other then what you said, do you think i got the right idea from her?
i mean, at first when we met the relationship between us was pretty good, i was so sure we were sharing the same idea, but as time went by i felt her backing up more and more, i think i might have pushed it.. what do you think?
but then again, why would she tell me 1 day before she left 3 times in a row that i could come and stay with her?
and when i asked her about that she started to back off?

was i doing something wrong?

if i would be going over there i would stay with her and her boyfriend, she has a big apartment.
thank you again for you replay

Its natural to back away from someone if you dont think your going to see them for a long while. Helps making leaving much easier. Its hard to say if you have read too much into this or if she was flirting with you even tho she has a BF. From what you have said tho she sounded like she was interested, not sure i like her way of going about it tho. If i had a boyfriend i would not be flirting with someone else and inviting him over to stay. Think about this a bit more and what she is doing to this BF. Could you really have a trusting relationship with this person. Knowing what she has/is doing this BF....This could be you in the future.....I would accept you had a good time and move on.

it's so hard to hear that but my heart is with her, i knew the moment i saw her.
thank you for you opinion it means a lot to me.

i think i will be ok if we ever be together, even if she leaves her boyfriend but i will feel bad about it.

can i at least tell her how i felt about what happened while she was here? tell her i will be waiting? or something in that way?

Gosh No thats going to far, keep a friendship with her first. Dont mean to be blunt here but what if she had a really good time and thats it its over for her. Dont put your life on hold....What if she never leaves him or never gets with you. Talk first see what happens dont take it too far and always remember the BF. Put yourself in his shoes for 5 mins.

see now that i got some more opinions i get a better picture of stuff, a different view on things.
now i think she would like to have a relationship but she can't because she has a boyfriend, so im like her 2nd chance kind of guy..
could that be?
i will not interfere with her relationship, but it's just too hard for me to accept at this moment and i want to know if i have a chance..