"I don't want a relationship outside of our friends with benefits thing, but I do want him to have feelings for me if he doesn't already."
Well, you're contradicting yourself here. You want it to be the same friends with benefits relationship but you're more or less wanting him to 'want you' or you're wanting him to fall for you in some way.
This is deceitful, at best.
The sex is the relationship and ultimately, you DO want to change the relationship although you're telling yourself that you don't.
This is called the bait-and-switch tactic. You give him a relationship that involves your mutual understanding that you're both in this for mutual satisfaction, you tell people on this website that the relationship is friends w/benefits and you're happy with it yet you want to make him somehow more affectionate and you're asking a question that would lead to your holding out on the sex in order to get something that you want more now.
This is what upsets all people involved in friends with benefits situations. One party will inevitably want something more even if both understood going into the situation that it was only going to be sex. Just because you're unable to control your feelings doesn't mean he should be subject to your manipulation tactics. ie; your holding out sex in order to gain a different type of relationship than currently agreed upon.
Whenever I see this situation come up, I cringe.