When I was single I had the same problem. Plus if I like someone I won't give anything away until I feel the feelings mutual. Infact I was more introverted around people that I fancied until I felt comfortable.
When I did the online dating one of my dates told me that if he seen me in a bar he would never have approached me?! I asked why, he said that my height (5ft 10 without heels) the way I dress, I can be reserved, I'm not loud and brash, he said he'd feel like I was too intimidating to approach!! I was like "i'm one of the most down to earth people you could meet! I'll talk to anyone" he said I know that because I got to know you before we met. Charming ?