I'm so sorry for what you are going through. I was diagnosed with a b/o in March as well. Total shock for us. Cause, like you, I got pregnant with DD fast, and had a healthy pregnancy, and never thought I'd have any issues. We got pregnant again right away in January, and then found out about the b/o. I can't tell you how scared I am to have that happen again. The image of the empty sac is forever etched in my mind, and I can't imagine going through it twice. My heart goes out to you. And if I were you, I would ask the doctor about some possible testing. Cause I don't think bf would have anything to do with a b/o.
I told DH that if I do experience another, I probably won't try to get pregnant again after that...simply because I know that I can't go through it multiple times. Not without answers from the doctor, more than just "it's just bad luck."