Well, I didn't have the exact situation as you. I was exposed to Chicken Pox when I was pregnant with my first child. It was very limited, but my dr too wasn't concerned enough. I then got the Chicken Pox as an adult 7 months after I had my second child. That child ended up getting them as well and just had shingles last year when he was three. My third child who wasn't immunized yet did not contract them from him at all.
What I know is that you would have to have direct contact with a weeping shingle lesion. My son's lesions didn't start weeping until well after we knew what was going on. I guess you would have to assess your time and direct contact to him. The first symptom would be a fever, so try to monitor yourself closely. Get some extra rest and keep up with your prenatals and water intake. I would have your doctor run a titer again.
Good luck to you. I know it is so hard not to worry about things like this, but you don't need the extra stress right now so try and fight the urge.
Let us know about your appointment!!!