I still find that the pocket is ever so slightly loose when I've got Jambin in the HAB, and it's been tht way since he was a newborn. The underneath crossover straps are always very firm and snug though, so I've never worried too much about it.

I position him so that his head is above my boobs - usually the top of his head is an inch or two below my chin. Any higher and I tend to bump his soft spot with my chin.

Jambin's head used to lol backwards too - I used to either put one of the straps over his head (I never did both, he always tilts to one side, so one strap was enough), or I'd hold his head with my hand to stop it bouncing around if I was walking. I find now that he's older (nearly 4 months) his head doesn't need support from either the strap or my hand. If your baby is uncomfy, they'll let you know!! If they're sleeping peacefully, then I always think they're probably not too uncomfy

HTH