Amber,
Here are my two cents (for what it is worth). I, too, could not do the "casual sex" thing. It is hard for me to separate sex and love. I also thought I was "missing out" on something and therefore, did the one-night-stands for a brief while. I found out that I disliked myself a little more each time I did it. I realized I couldn't change something that was part of my core, and just because I didn't enjoy casual sex, didn't mean I was "defective." You can't be someone you aren't.
There may come a time when you feel you will be able to enter into casual sex without attachments, but enjoy who you are now. I don't judge those who are able to have casual sex. It works for them. It just doesn't work for me. Being different from each other is what makes life interesting.
Just embrace who you are and be comfortable with that.
You will be glad you stayed true to whoever you are.
Buena suerte,
Tondra