mobs spawning a lot even when on easy

This realm's difficulty was originally set on normal but there were 3 mobs spawning at a time so we thought it was weird. We set it to easy and it's still spawning at the same rate and there's a lot even though we lit up the place with tons of torches. 

There's also an invisible creature hitting us on some nights. At first we thought it was phantoms and silverfish but it's in our houses with roofs on them so I'm not sure what it could be.