She may just like her own body. Men can do it, why can't women. Ad if your only her boyfriend maybe that's why she didn't send it to you. Sexting has become an awful epidemic. Girls committing suicide and all kinds of stuff. Maybe she's afraid that if she sends it that it will be sent out. Maybe not on purpose, maybe your friends go through your phone and see it, or even worse send it to themselves. I'm not saying there is no possibility she took it for someone else, she could have. But there is a chance that she just wanted it for herself.