I just wanted to chime in and say a couple of things.
First of all, the fact that your H told you straight up that he would like it if you were more assertive, is really GOOD news. That means that if you do become more assertive, he will likely not only respond, but he will also get more assertive himself, over time.
It seems that maybe you have done too good of a job becoming the girl your parents raised you to be. Unfortunately, "that" girl is too timid for a man to feel very sexual about. You have likely given your H the idea that you aren't that interested in sex, or that you do not want it any more often than you are already doing it. Regardless of talking to him about it before, you probably did not give him the message you thought you gave him, because if your actions are totally non-assertive, then he is going to read your actions more often than the occasional conversation you bring up.
The way to be assertive without nagging is to show him and tell him you want to have sex with him. No man (with a normal sex drive) is going to view you wanting sex with him as "nagging"! Instead, it is going to make him feel desired, which will then trigger his desire. Over time, as you show him your desire for him, he will likely show you his desire for you more! So instead of waiting for him to bring it up again later that night, you just get in bed in a sexy nightie and light candles...and you tell him straight up, "baby, I can't wait to get my arms around you and make magic together".
When Lucky said to make sure you don't make it seem about your own satisfaction, I think what she meant was to make sure he feels desired by you. IE: its not that you "want sex", its that you "want HIM". This should be an easy message to deliver to him, if in fact, you really do want him. You like the way he looks? Tell him. You like how muscular his legs are? Touch them and talk about how sexy they are. You love it when you get to look into his eyes while he's making love to you? Send him an email the day after sex stating this.
