It means either she has got tired of you or you are invading her personal space. If it's the first then to not talk with her would be the best option, but in the second case, you need to let go a bit if you want her in the romantic sense, nobody likes to date a stalker!!
stop being nasty
It means she is happy with not being in a relationship.
Shes either being sarcastic or shes impressed
She could be flirting with you or just being mean.
nothing
That would simply mean she enjoys being around you and misses you.
Obviously, being a girl, she likes you.
It usually means a girl is wearing a tail. She is being followed. I guess it could also mean she has a nice rearrnd.
Are. You. There
If you tell a girl that you love her and she says that it's a strong word what does that mean?
When a girl says that you not bad means that she thinks you are a nice person. This could also mean that she likes you.
Nothing she is just being friendly. Actually, this answer by just being 'friendly' isnt completely true, sometimes if she does so, it could mean she is interested in you.