Sizing

I sat still, not daring to say a word as my mother-in-law approached me, lifted my skirt, pulled aside my panties. She looked down, a cross look on her face. 

"What?" my wife asked.

"This is unacceptable," my mother-in-law said. 

"Unacceptable? You...you said to use a cage," my wife said.

"A properly fitted cage," my mother-in-law responded. "Look at this, there's half an inch at the end, maybe more."

"I got the small one," my wife said.

"Then you should have used another brand," my mother-in-law scolded my wife. "A cage is supposed to be tight at all times, a cage is supposed to prevent even the slightest hint of swelling. My god, she can practically grow erect."

"Mother," my wife said.

"Don't mother me," she said. "I'll send you a link to a 3D printed version a company makes. Order the baby size, it's less than an inch and a half. It may be tight at first, but she'll grow used to it. Pardon my pun."

I looked up at my mother-in-law, wisely bit off my comment at the last second. 

"A sissy is to be kept as small as possible at all times, it should never swell, even a millimeter. Oh, it will miss it at first, but it will soon forget what it was like."