Have you been put on anti-spasmodics? The fact that the incontinence is coming at night suggests IBS or spasmodic pouch (excessive motility), and is correctable by taking anti-spasmodics like bentyl or levsin 45 minutes before meals and at bedtime. I had this issue in the years after takedown, not so much since. The failure of the antibiotics tends to discount SIBO.
Because you are pregnant, they may not want you on those kinds of drugs as they have side effects that can make you loopy/lethargic. Being pregnant could complicate things in terms of treatment. You may have to deal with it for the balance of the pregnancy. I am guessing if they did not put you on anti-spasmodics, that could be why.
I found that donnatal was better than bentyl or levsin for spasmodic pouch (less side effects). It was taken off the market at some point- not sure why- and I am not sure if it is available now.