Questions: Flirting

This girl knows i like her. I am planning to ask her out soon...When we are in group at times she flirts and teases me a lot and spks well. But sumtyms she spks to evry1 but me. But evry now and then she Looks at me when i am not looking at her. Her eyes change so quick i can see through peripheral clearly she looks at me when i look side not at her. When i turn to see her when i realize she looks at me. Split second she changes her eyes sideways. I dont show that i caught her. When i talk to her she brightens and responds with nod and smile in her face. But all i get is mixed signals.. when i try to talk to her alone. She is little bit awkward and uncomfy vibe. What shall i do to make her comfy. I am putting up with all her shit tests or watevr. She replies my text and calls me sometimes and nvr return my call i call very less. She smiles at me and her face nvr show disinterest. I know i can get this cleared by asking her out. But is she intrsd with my words?

I used to hit the gym quite regularly until I went to college and was fairly ripped/athletic. However, after a couple of years in college, I've dropped like 20 lbs and become kind of skinny. I just have long thin stripes of muscle and if I lose any more weight my ribs will probably start to show.
As a result, my self-esteem seems to have taken a hit (spectacularly failed relationships in the recent past haven't helped in that regard either).

Anyway, my question is, would you, ceteris paribus, think twice about dating a guy who looks like a human skeleton.
Provided he is not a douchebag, is reasonably intelligent, and emotionally available.

Most girls that I know say it doesn't really matter, but I'm not so sure. I mean, I can see a marked difference in my interactions with the opposite sex now, even though I'm definitely a lot more emotionally mature now than I was earlier.