Small rats are likely quite large for him. It depends on the supplier but most call 45-85 gm 'small' and some like mine is 60-95gm typically I'd feed about 10% per feeding. Adults get less that 10% as they are not growing as quickly. hatchlings get 10% but a little closer together every 5 days or so rather than every 7, give or take.
Are you weighing the rats?
It very easily could be yours letting you know those are big meals and to give her time to digest. Either drop back down a size or longer between meals. Just remember no larger around than the snake is.