RH Negative And Questions😣

Ye
So I Am 0 negative and I'm a little nervous about this shot that I'm suppose to get at 28 weeks I am now 26 weeks... I've herd that it's really painfull... and I was also wondering if by 28 weeks ur supposed to get the shot..could I have gotten it earlier?? I'm just concerned on my baby girl I wouldn't want anything too happen too her 😔 Also Any RH Negative Mommies Out There?? What was your experience like?