Flirting

This isn't really a serious issue, but ever since I was young I can't tell if people are "checking me out". I notice people staring at me but because I have anxiety I assume at best they are staring off into space, at worst they are thinking negative things about me. Like "Wow, she looks weird. Who let her in here?" This isn't as much of an issue anymore because I am no longer looking for a new partner, I have a bf I am very happy with. But I can't even tell when he is checking me out because I avoid looking at people's eyes and I assume he is just staring off into space if I do catch him. I only know when he admits it. How can I tell?! I feel like an idiot for not being able to notice such a simple thing. I think my anxiety is making it hard for me to recognize when people actually are interested in me. Anyone else with anxiety got any tips?