My placenta is against my back but I still don't feel a lot of movement. I've felt one, maybe two, actual kicks. One was during my MW appointment and I felt it right after I said I've hardly felt any movements.

Depending on who you ask, I'm either 20w (according to my LMP alone), 20w6d (according to the ultrasound technician and my fundal height measurement), or 21w2d (according to my NFP chart).
DH has not felt movement yet. I haven't even felt movement from the outside, even when I poke and prod.
I don't think you have anything to worry about right now, honestly. I have had one kid who I swear had nightly parties in the womb with five or six of his closest friends. I never stopped feeling him move. My most recent baby was always incredibly mellow in the womb, and at 16 months, she is still very mellow and quiet. It could be personality more than placenta location.

I keep telling myself the same thing, btw - I might want to feel those strong kicks now, but I will regret it the very second this baby discovers my ribs!