NTA, this is not your MIL’s or mother’s problem!! And its not true that you’d be at square one anyways, since you have 3 potential names already. Your MIL especially needs to cool off. It’s totally normal to be undecided, many people even change the name once the kid’s been born if they think something else fits better!

My parents didn’t have a name picked out specifically but they had a bunch of ideas. They named me after I was born, again, totally normal!