When we talk about security in a relationship, we really mean confidence. There is nothing men hate more than feeling that they have to check in every five minutes so you know where they are and what they're doing. They shouldn't have to tell you that you're beautiful five times a day when they show it with their behavior and they say it when the mood is right.
Be confident in yourself. Feel sexy. Feel strong. These are some of the qualities he likely fell in love with in the first place, so keep hold of him. Trust him to keep to his promises, and to love and respect you the way he's told you he will. He doesn't want a mother looking out for him and smothering him; he wants a lover.