(Photo credit: Carter Smith for ELLE)

When Kate Upton landed her first "Sports Illustrated" swimsuit issue cover, she should have been on top of the world - but she wasn't.

Instead, "I felt terrible about myself for a solid month," she told Elle magazine for its September issue. "Every single guy I met was either married or about to be married, and I felt like I was their bachelor present or something. I'm not a toy, I'm a human. I'm not here to be used. I am a grown woman, and you need to figure your s-t out."

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Upton, 21, added that even in the modeling industry, there are misconceptions of who she is - and she's learned to use that to her advantage.

"People deal with models like they are children. They think they can pull one over on you," she said. "It's actually funny. I'm always like, 'I'm about to pull something on you, and you're so focused on thinking I'm dumb you're not even going to know.'"

There's also an assumption that Upton, who attended an Episcopal prep school and has a cross tattoo on her finger, is not religious, she said. That's not the case.

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"I was at a photo shoot and I was wearing a cross necklace that my mom bought me, and somebody made a joke like, 'Why are you wearing a cross? Like you would be religious," she recalled. "Then they took [my necklace] away. I was really affected by that. The whole thing made me realize that I do want [a cross] with me, at all times."

The model also cleared up rumors about her dating life.

"I really have never had a serious relationship in the industry. I'm just having fun," she said. "Obviously I have a very busy schedule at this time in my life, and I don't put relationships as a priority."