Your question is not meaningful. You're thinking in 3, maybe 4 (space+time) dimensions.
It's like asksing, "Who made God?" That's another question that assumes 4 dimensions.
Why regress the expansion only back to the size of a peach.? Einstein, Hubble, Eddington, Hoyl, Wilson, Penzias, and many others regress back beyond the peach to ex nihlo universe. Then suddenly......the universe came to be.