I feel like a pervert after checking out this girl's picture online.
Are you leaving something out? I don't get what made you feel like a pervert.
A young lady uploaded an image on Facebook. I had seen her somewhere before and I was staring.
I don't think you're a pervert. You're just curious about the girl and there is nothing wrong with that.
I think I feel like a pervert since I want to know about her, I think I'm obsessed with her.
Sometimes we can be so curious about someone that it feels like obsession. This isn't the same thing as a perverted attraction, but if you feel the obsession is slightly sexual you need to do something about it.