One of the biggest mistakes I made with my boyfriend in the beginning is trying to keep his relationship with me within strict parameters; he was supposed to be my "f*ck buddy", but we just clicked so well that trying to restrict our feelings was futile.
Keeping within the same spirit, trying to make a relationship more than what it is can be off-putting, as well. Every relationship is different, sometimes you just have to let it grow to see where it will lead, and make sure there is respect/consent/understanding among all those involved.
You and your husband seem like a very understanding, loving couple. Good luck.