Does it seem like she is interested and if so should i keep on flirting?

I just started working with this girl who I found out is a lesbian but has a gf whereas I am single. I am a lesbian too which she knows. Her girlfriend came visited her work tonight as her gf wanted to meet me (which means I assume she has told her all about me after working with her once). She told her gf that I was an older version of her. I catch her looking at me everytime I look at her to check her out and smiling. I just keep looking at her and smile then look away shyly. She said I should have a drink after I knock off (as she is still working at the pub). I asked her questions also and she remembered and reanswered a few things the next day eg I asked who was the boy/girl in the relationship and she reanswered it today. She also asked me whats the youngest I would go as she is early 20s i am late 20s. She is definitely my type and I find her really hot and am always of the opinion that if I am not the one in the reletionship then its fair game. Her gf told her if she put on weight she would almost be as hot as this other girl. I told her that her gf must be blind or crazy. Why would her gf come visit her work maybe she is paranoid to want to meet me since ive only worked one shift with her girl. Also the other workers say she never comes in to visit normally.