Should I go back...

So yesterday was the first day my LO was in size 1 diapers. He was born 6 week premature, was in premie clothes and diapers until he was 1 month old then went to new born clothes and diapers. He was 4lbs 4oz at birth and is now 9lbs 11 oz.

We ran out of new born diapers yesterday and I put him in 1s. To my amazement they are huge on him! The back of the diaper goes almost to his shoulder blades and the front come to the bottom part of his ribs. Last night he was soaked after his 5 hr sleep stretch, and I think it is because they are so big.

New born diapers fit him pretty good still, the straps have about a half inch between them touching but they no longer hold his poo in.

The pic is him at his 2 month appt in a new born diaper. He is still in New born clothing.

So my question is should I put him back in new born diapers for a bit longer or just deal with the big diapers and the leaks?