Sounds like you need to have more twist in it... :)

The 'pull-off' isn't just taking your third finger off leaving the first finger fretting a lower note (for instance)... to get the same volume you'll need to kinda flick your third finger off the string... I pull down

Not sure if I've explained it well, but yeah, you need to pluck the string a little with the finger on your fretting hand to get the volume on the note you're pulling off to...

Picking the first note harder would give you more volume, but without a bit of a flick on the pull off the volume will still be uneven. Try trilling between two notes to get the volume between hammers/pulls even...