To make your baby a little bit smaller like this open up Reshacker and click on the Lnz tab and open BabyMaster.
Find the part that says:
100 normal pet scale
100 normal ball scale
Change the pet scale to 95 and leave the ball scale as 100. But you can of course fiddle about with these numbers to find a size you like.
Thanks to Gabi for helping me with this. Mwah!