My hands are quite small so I sized down. I also did not use a ch 1 at the beginning of each round. Maybe I was doing it wrong, but I created a gap that I didn’t like. I used a piece of contrasting yarn to track rounds.

This is how I wrote it down to replicate with the second mitten:

Magic circle
Ch 1
8 hdc in cricle
2hdc around (end with 16 hdc)
2hdc, hdc, repeat (end with 24 hdc)
Hdc until row 16 (or as needed to fit to hand)
Hdc in 3, chain 8 (I increased the size of the thumb hole), skip 2 stitches, hdc rest of round
Hdc 3 rows
Hdc in 6, hdc2tog, hdc in 12, hdc2tog, hdc rest of round
Hdc around
Hdc in 2, hdc2tog, repeat
Hdc 5 rows, tie off