Can someone lack empathy?

I have been with my girlfriend for about 8 years now. I have been in several long relationships before...this is her first. Here is a quick list of some of the things my girlfriend does...When we are out she often stairs at other guys in public with this weird glazed over smiling expression - She steals money from her parents (her parents know she does, but never say anything) - She tries to join in on everything I do and when she does she messes everything up (for example I paid to get her a Real Estate license and when she dealt with clients she would mess up doentation that could have had serious consequences if I didn't always look over her shoulder). That is just a few examples, but the impression I want to give is that she seems very mentally immature (as in she doesn't seem capable of functioning in society) and the kicker is that she doesn't seem to even notice. I am a very patience and logical person and I have been with her for awhile now...but I have never met someone like this...like she will sneeze in my food and if I catch her and get on her about it she will say "I'm sorry" but I truly believe she doesn't even understand that what she just did was very disgusting. Do you have any idea what this might be. P.S. - she did go to a Psychiatrist...the istant said she had narcissism but the doctor said there was nothing wrong with her (which I believe just reinforced her belief that everything she does is okay). I would really like to help her if that is possible.