MIL throwing around our possible name

Missy

My husband and I have had a hard time finding a name for our baby boy due in Oct.

We found a few names and my mother in law went through them. She has been using one name in particular and throwing it around as if we have already chosen.

The thing is... We told her we weren't naming the baby until we met him.

We want to be the the ones to chose his name as his parents.

I almost don't want to consider the name just because she's telling everyone the name. I'm upset by this and not sure how I can fix the situation at this point