Wanted kids, but now I don't

When I was a teenager and early in college, I desperately knew I wanted kids (not at that point in time, but one day). I thought as soon as I get married, my husband and I would TTC right away, because my desire was so strong. I've been married for 5 months (together for 7 years) and I don't have that urge - I've even lost the urge for sex about 3 or 4 years ago- I'm never in the mood! Has this happened to anyone else? Is this something I should be concerned about?