The one-liner I would use in this situation is,

"Are you trying to be [insert word here]?" (rude, insenstive, mean,
horrible, nasty, etc).

If they say they are telling you because you care, then:

"I can do without your kind of care"

Easy! It isn't fair of people to get you upset - I think it is just
nasty.

I am a Midwife, and when we get on the subject of birth at work (which um,
happens quite often!) and I tell people I am considering a home birth for my
first baby, some people roll their eyes, and make disapproving clicking
sounds with their tongues, as if I won't be able to handle it, etc. One
woman (a nurse, not Midwife) said, "OOh I'd love to be a fly on the wall for
your labour!" How mean is that?

It IS really frustrating, mean and rude. You need to let them know that.

Good luck! Your birth sounds like it will be a fantastic experience with
those care-givers!

Jo (RM)