That your male friend told you several women at work find you attractive is an important piece of the puzzle. If they didn't find you attractive they wouldn't waste their time talking about you, unless you were so obnoxious you made everyone miserable. If you've followed my column on a regular basis, you already know I am against going out with people you work with because it creates more problems than it solves. You're absolutely correct, vanity and conceit are based on insecurity. And the insecurity rarely has anything to do with the person's physical appearance.
Vanity is a result of insecurity, as is conceit.
Rather than concentrate on the negative, let's concentrate on the positive. At the root is a healthy self acceptance and self love. Not a narcissistic love, but a genuine caring about one's self. To solve this problem, I tell my students to make a list of all of the qualities they would like to attain. And then I have them write down the definition of what those qualities mean to them.