Can you post a pic of the hammock? I have an Amby and you place bub down the bottom so basically their feet almost touch the end and because of the ties at the top where it connects to the springs you can adjust the incline if that makes sense. So I could tie it a bit tighter to raise the head end slightly. He never had his bum higher at any stage though... so I would suggest without seeing a pic of your hammock that bubs may need to be placed a little more towards the bottom of the hammock??

I have a pic which shows fairly well how close to the bottom of the hammock Oskar was.... if you click on his name and then click on photos and go to the one Oskar Levi 12 wks - 4 months there's a pic about the 5th one I think it is.... hope that might help you a bit. PM me if you get a pic and I'll help more if I can