sold home to our son without any gains on home sale?

Last year, we had our son, and his wife took over the primary house we have in Texas.  We did not gain any extra income from the transfer. We basically wanted to refi the house into his name, however, we were told that it has to be a sale in order for our son and his wife to own the house.  So, we sold the house to him and his wife, in the amount of whatever was the balance remaining on our mortgage to pay it off.  I have not so far received any tax document regarding the sale. I read that normally when there's a gain in selling a house, you will receive a 1099-S which we have not since there was no extra income gain, do we need to report this to the IRS? If so, what section in the Turbo Tax we do.  We only received the usual 1098 document from our mortgage company nothing else.  In reviewing the closing documents, there's a form called substitute Form 1099-S Proceeds from Real Estate Transactions.  The Gross Proceeds amount is the same as the Allocation of Gross Proceed, not sure what this means.