Jeff decided to make her a toddler the tender young age of 2. That way she'd be older but still be in and need diapers like she wanted, for whatever reason.
Quickly making the simple alteration of changing the 16 to a 2, Jeff was about to hit the execute button when he thought of another minor adjustment to make. Once done he hit enter then sat back to watch as the transformation took place.
The entire regression happened fairly quickly as he saw Jenny go back through puberty, then childhood before coming to a rest in the middle of toddlerhood; all the while sucking her thumb the entire time she grew younger.
The newly regressed baby girl looked herself over in surprise and awe. Her previously shoulder length red hair was now short like a boy's through just long enough to be done up in two cute pigtails. Her small body was now a bit chubby with unshed baby fat and her boobs were gone leaving her flat chested, visible thanks to all her clothes disappearing. All except for her panties which had changed into the very thing she had requested, a Pampers disposable diaper.
"Since you said you wanted to wear diapers I make it so that would be all you were wearing" Jeff admitted.
However his toddler girlfriend barely heard him as she was still admiring her youthened form.
"Holy cow, is this really for real?" she said to herself as the realization dawned on her that the answer was yes.
When it did Jenny began to dash around the room in excitement, jumping and skipping with joy. Since she was wearing the crusiers brand of Pampers she had complete freedom of movement.
"Weeee! I'm a baby again and I'm in diapers!" she cheered.
Running for a couple more minutes an out of breath Jenny toddled back to stand before Jeff.
"Believe me now?" he said with a smug grin.
Jenny nodded her head. "Uh huh. This is totally amazing and you even managed to pick the perfect age" she beamed.
Her happy expression then changed to one of mild discomfort.
"Uh oh."
"What's wrong?" Jeff asked in alarm.
"I gotta go potty" Jenny replied seconds before she started...