Tula - newborn insert?

Hi guys, I have a Tula explore on loan from my local sling library. However my 12 week old doesn’t seem to love it. She’s on the smaller side (9th centile). I’m hoping to try the Tula Free to Grow at our next sling meet up.

I’m just wondering

1. Which carrier people think is better for a 12 week old on the smaller side?
2. Any tips for helping baby to enjoy baby wearing
3. Do I need the newborn insert for the Explore or Free to Grow if baby is on smaller side?