The power you have as a contracting officer (KO) or even the contract specialist is more than just the authority of the FAR; you have reputation power.
“The CO said you can do that”; “The CO said you can’t do that.”
That’s a lot of power because it can mean not using a small business or getting a better deal. When you say yes or no, make sure you have evidence. Remember: assertion + evidence = you know what you’re talking about.
P.S. I don’t get this right every time either, but I keep trying (as should you). It’s how we get better.