How will you know if someone is interested in you?

 So I have a hard time knowing if this girl interests me or not, and I would like to know your opinion. We work at the same place, I met her 5 months ago. At first, I didn't mind, but a month later I started to have a big crush on her. She is kind, cute, and smart.

When we first speak, we make a connection when we talk about our goals, dreams, and personal dramas. She told me she had a boyfriend but she had some problems with him (in response, I don't know what kind of problems, roughly, she said they were pretty distant) . Anyway, so far there has been nothing romantic, except that in September she flirted with me a little (she touched my back and arms, played with my tie, used my personal belongings, and watches, and we were alone) but this type of flirting stopped in November. We always chat and have a little fun in a group, but when we're alone, she's a little embarrassed (ask how her day was and she gave me a short answer) and she sees that

A week ago we spoke to her and told her that I went to a wedding party, she said she wanted to go too and pointed out to me that her boyfriend's cousin was getting married next January, but she's not sure she wants to go with him, because she doesn't want to be with her family and she still has problems with her boyfriend (she even said that she doesn't want to present herself as being his girlfriend)

What do you guys/girls think? Am I thinking too much, is there a possibility that she has an interest in me, or thinks of me as her backup boyfriend? Should I pass?

THANKS!

How can you know if someone is interested in you?

So I am having a problem trying to know if this girl is interested in me or not, and I would like to know your opinions. We work in the same place, I met her 5 months ago. At first, I didn't mind her, but one month later I started to have a big crush on her. She is kind, cute, and smart.

When we first talk, we make a connection when we talk about our goals, dreams, and personal drama. She told me that she has a boyfriend but she is having some problems with him (atm I don't know what kind of problems, at much she said they are kind of distant). Anyway, until now nothing romantic has happened, except that in September, she flirted with me a little bit (touched me on my back and arms, play with my tie, used my personal things aka watches, and even approach my personal space when we were alone) but those type of flirtation stopped at November. We still talk and have some fun in a group, but when we are alone, she is a little bit awkward (ask how was her day and she gave me a short answer) and it seems she doesn't want to talk with me. 

A week ago, we were talking and told her that I went to a wedding party, she said that she wanted to go too and commented to me that the cousin of his boyfriend is having a wedding next January, but she is not sure if she wants to go with him, because she doesn't want to be with his family and she still has some trouble with his boyfriend (she even said that she didn't want to introduces as his GF) 

What do you guys/girls think? Do I am thinking too much, is there a possibility that she has some interest in me, or she thinks of me as her boyfriend's backup? Should I move on?