L.A.
I would call your ob. They will have you come in for a blood test that can tell if you have had it. Unfortunately it wont tell you when you had it. If you did catch it though then they can check out the baby.
I know it is not hard to stress. I did when my son had it and I was 6 months pregnant. Those websites freaked me out even more. The dr.s told me I probably would have known it if I had caught it through my son. And the chances of me catching it were pretty slim since it was mainly transferred through saliva.
My tests showed I had never caught it.
Good Luck to you! Take a deep breath and try not to stress (easier said than done-I know)