None of the Realtors have given you the right answer.
If you haven't signed a buyer agent agreement, you're OK. The brokers however, are not. The broker who showed you the house can go after the commission of broker that wrote up the offer. The broker who showed you the house can say "I showed the buyer the house, I deserve part or all of the commission". A broker is not supposed to write up an offer with you if he knows you've already seen it with another broker.
If you did sign a buyer agency agreement with broker A and wrote up an offer with broker B, you might owe a commission to broker A. And by the way, broker B knows this.
You might want to bring everything you've signed to a real estate attorney before you go any further.
A similar situation happened to me. I walked into an open house and did not tell the broker on duty that I was working with another broker. This was years ago before there was such a thing as buyer & sellers brokers. My broker told me that if I wrote up an offer with him and the broker at the open house recognized my name, he might not get paid. My broker told me in the future, to write his name into the open house register next to mine.