Small apartment 2 kids

So I live in a 2 bedroom apartment with a 3 month old and a 1 1/2 year old. They have both adjusted very well to each other’s crying. But I still find I’m keeping my 1 1/2 year old from trying to make noise while babys sleeping snd I feel bad... it gets exhausting always worrying if the baby will wake. I try to do fun quiet activities while baby sleeps but doesn’t always work out. Even in the morning when my husband goes to work he has to shower get dressed and all that and even though he’s quiet, my 1 1/2 year old always wakes up. Anyone else in the same boat, have any advice or tips?