Moving to cot

Hi mommy's

My 3.5 month old baby is really active day and night since birth she sleeps in a next to me crib but the last few weeks she's moves a lot and somehow managed to end up in my bed🤔🤣

So I would like to move her into her cot bed that will go into

our room until she is at least 6 months I don't have a bumper in the cot because I don't want her to suffocate

My question is should I use a breathable cot liner or just nothing in her cot??

Because she moves so much I am scared she will get her arms stuck

What would you do??