That's not "sluthood." There is no predetermined action that makes you a slut. Unfortunately, in Western cultures, sex is a taboo subject, and often a subject of shame, especially for women. Coming from my own experience, being sexual, having desires, and engaging in any action that isn't "standard" for a woman brings about feelings of shame because we're not supposed to be sexual.
You're starting to feel at ease with your sexual desires and it doesn't seem like you know how to handle them. That's okay. In my own experience, it seems our culture has also prolonged the development of identity - more people are living at home longer, going to college and still remaining dependent on their parents. This isn't a bad thing; what makes it potentially negative is that we come to terms with our identity and capabilities at a later age than what society expects.
By our mid-20s, most people come to terms with their identity, "who they are," so to speak....sexuality, strengths, weaknesses, desires, ambition, you name it. You get a sense of ownership over what you've done with your life and what has yet to be achieved.
I've learned that people who don't get this sense of ownership in this world by this age marker (which you can't escape from, the world expects this from you), they often turn to common things and try to own them in their own way - sex, drugs, and other things of "rebelliousness" teenagers often engage in. Why those subjects? Because it's what they know. It's a quick, accessible subject and can give you an immediate sense of self. You can point to this "thing," and say "I'm good at that. It's what I know I can give to people." Sex can give that feeling of ownership to people.
Can you identify with anything I've typed out here?
You would really benefit from seeing a counselor. You guys could definitely explore what's going on and perhaps what's going in your head that's making you turn to sex. If what I've typed out is true for you, you could work with that and build upon it.
There is no shame in sexuality. Giving in to that primal desire, breaking down your inhibition and letting go. You feel like an animal.....at least, for me
Go see a counselor, and make sure you're being smart about your sexual partners. If you're sharing nude photos, DO NOT include your face and use an anonymous email. Make sure it's not associated with your personal email, AT ALL. If you don't want these photos to pop up later and bite you in the ass, you need to be as anonymous as possible. I'm all for exploring your sexuality, but not when it can be used for blackmail.
If you're meeting people online, that's also a danger - get to know them first before you sleep with them. That can at least put up a small barrier between you and the crazy assholes who might try to hurt you.
Get tested REGULARLY - if you're active, do it at least every six months. Make sure you're seeing a gyno for regular exams.
Wear a condom and do not let them convince you otherwise. If they keep trying to persuade you not to do it, walk away. There are "thin" condoms out there that can improve sensation for him (my recommendation is Trojan Bareskin). ALWAYS ask him, before you have sex, to show you proof that he's been tested and is clean. Yeah, it's a mood-killer, but if you are having a one-night-stand, tuck away your libido for five minutes and have him show you the paperwork proof that he's clean. Just because he's pretty and well-hung doesn't mean he won't lie to you. If you want to make it really hot, tell him to show you and if he does, you'll blow him or let him blow his load on your boobs. Guys love to jizz all over things.