Have you tried to feel your fundus? It should be an inch or two below your navel. This is how much room your baby has to move about in at the moment, so I don't think it's unusual that you can feel movements so low down.
hi disenchanted, i remember you from the ttc thread we were on. I cant remember if this is your first or not but im 22 weeks and asked my m/w same sort of Q yesterday as this is my 2nd and it kicks about soooo low it almost feels v wrong! She said that with 2nd etc babies its because the pelvic floor muscle is alot lower so you feel it lower also depends how baby is lying. Mine is facing down and laying sort of diagonally and has been for a while so im having hands aswell as feet moving around!
Granted, its an odd feeling! Wont be long before your wishing you could go back to low kicks once it gets huge and they;re all in your ribs!