My Missy turns six months at the end of April and I know that it is said that they should be spayed at about this age, but I am not sure if she's ready or rather if I can bear it

! Missy is 4.3 lbs, and surely she is healthy and large enough to have the surgery, but I can't bear to think of her in any pain and I also can't help thinking that once it's done it can't be undone. I know I have to do it soon, so I want to at least have everything ready.
Her regular vet is about 35 miles away in Brooklyn, NY (40 minutes from my home), and the only reason I used this vet was that they were recommended by the breeder. I really would rather have a vet nearby that is recommended and that has done spaying so that after the surgery I could get her home fairly quickly.
If anyone knows of a reputable vet nearby South Plainfield, NJ (or somewhere in Middlesex county NJ) where they had their Yorkie spayed successfully with no complications, please do respond.
Any additional information would be graciously appreciated.
Thanks!