Sidecar crib

So my daughter is 11 months old and has been sleeping in bed with me practically for forever. Im trying to transition her in her crib but i still breastfeed her throughout the night so I figured doing this would be easier. The only problem is that the crib mattress is a little tiny bit higher so it’s a little hard for me to breastfeed her like that at night.. idk she’s very attached to me (as I am to her) so throughout the night she also wiggles around and crawls over to me in bed to feel me and hold my boobs.. anyway lol does anyone have any tips for leveling out mattresses the same height?