You and your mother are right. That is exactly what the analogy is used to explain. However, I used it in a sense that cohabitation is usually viewed as an extreme extension of pre-marital sex. (Undacuva's post dispelled this). I guess what I was trying to say was why marry, when you can have all the non-legal benefits of marriage without tying the knot?
And to answer your question, I do believe you should wait till marriage for sex. And yes, I am male!
To sum it all up, I paraphrase what Japera said: It's up to you and yours.