"Look at these things!" Alyssa thought, picking up the satin briefs. They were absolutely enormous to her, although the fabric felt really nice. "If only they were my size," she lamented, rubbing the high-quality fabric between her fingers.
"I guess since I left the receipt, and I can;t return them," Alyssa thought, looking wistfully at her reflection in the mirror. A girl just over five feet tall, with light brown mid-back-length hair and a light dusting of freckles across her youthful face stared back. Alyssa ran a hand over her hips, pursing her lips and staring at the mirror. She had recently upgraded her bras from the training bras of 8th grade to more womanly underwires appropriate for a high school freshman. Her pert breasts filled the A-cups nicely, promising that soon she'd need to pick up a B-cup.
A strange urge suddenly came over Alyssa. Maybe she could put these big panties on and go the rest of the night wearing them, under her shorts. No one would know, after all. For some reason, the idea of wearing underwear meant for someone much older kind of turned Alyssa on a bit. She often fantasized about what her body would look like when she was 20, or even 30 years old. Her mother had a pretty good shape, as far as moms go. She had been a volleyball player in college, but having three kids had added plenty of weight in the hips, butt, and chest. But she knew how to rock her body. Sometimes, and much to her kids' embarrassment, she'd put on yoga pants when they went out. Alyssa would roll her eyes, but she couldn't deny that her mom attracted some admiring stares from guys on the street.
Almost imperceptibly, Alyssa had slipped her finger beneath the waistband of her panties, intent on removing them. She shrugged and bent over, pulling her plain white panties from her body. Next, she stepped into the "Mother's Plus Collection" briefs and pulled them all the way up. She felt a rush in the pit of her stomach as she pulled them tight, and her knees even buckled a little bit.
"Whoa, that was weird," she said, regaining her balance. She looked at herself in the mirror and smiled a silly smile. There looking back was the same 13-year-old girl, only wearing huge underwear meant for someone much bigger. The satin felt nice on her skin, but bagged and wrinkled anywhere it could. The elastic on the waistband clung to her hips, but only barely.
"Alyssa! It's time for dinner!" She heard her mom call from down the hallway. She snatched a pair of soffe shorts from her floor, put them on over the enormous panties, and joined her family for dinner.
Alyssa took her usual seat across the table from her 5th-grade brother, Davis, and her 7th grade sister, Claire. Her mom was on the right and her dad on the left. The family ate and talked, mostly about the new school year. Shortly after beginning to eat, Alyssa felt the same swooshing sensation as before. Her hand shook, causing the broccoli impaled on the tines to fall to her plate with a splat. Claire giggled, and Alyssa shot her a dirty look.
Alyssa soon noticed that her bra felt like it was digging into her ribcage. And her shorts were riding up her thigh a bit. She adjusted them as nonchalantly as she could, while her brother talked about catching Pokemon using his newly downloaded Pokemon Go app.
A few minutes later, the same feeling swept over Alyssa, this time causing her to gasp and grab onto the edge of the table for support. Her bra dug further into her ribs, and her shorts felt like they were giving her a wedgie.
"Alyssa, are you okay?" Her dad asked, raising an eyebrow.
"Yeah, I-I'm fine," she said, trying to play it off. "Just remembered I have some more stuff to do before school tomorrow." She stood from her chair, accidentally bumping the table with her butt as she turned to leave.
"Haha, Alyssa's gotta big butt!" Davis teased. Ayssa ignored him, putting her plate in the sink and walking to her room as casually as she dared.
"Our little girl sure is growing up," Alyssa's mom said as she watched her daughter walk down the hall.
Back in her room, Alyssa closed the door and looked at herself in the mirror. She couldn't believe what she saw. It looked like a college-aged version of herself staring back. The t-shirt and A-cup underwire bra were stretched to their limit, and her soffe shorts clung to her wider hips and fuller butt like a pair of spankies.
She quickly tore off her undersized clothing and stood only in her panties. "What the hell!?" She whispered under her breath. She now sported C-cup breasts and curvy hips, which did a much better job filling out the satin panties. While still a bit loose, the panties now had no problem staying on her hips.
Even as she watched, another swooshing sensation overtook her. She moaned out loud, her knees buckling, as she saw her reflection change again. Her breasts expanded in front of her eyes, going from pert C-cups to heavy D-cups. The swelling sensation was accompanied by a sloshing, and she realized that they were laden with milk.
Meanwhile, her hips and butt inflated like a balloon, filling out the panties marvelously. The high-cut satin briefs now looked perfectly natural on her matronly figure. Heck, she could giver her mother a run for her money in the measurements department.
"Wha-what's happening to me?" Alyssa asked her reflection. She ran to her door and cracked it open, listening. Her family was still talking at the dinner table, so Alyssa opened the door silently and sprinted down the hall to her parents' room. Digging through her mother's dressed, she pulled out a bra, then returned to her own room. With a bit of difficulty, she squeezed her shapely breasts into the cups. It looked like she now had the biggest bust in the house!
She turned and looked in the mirror again. A 34-year-old mother looked back, with just enough weight in the hips and butt to make her matronly, but not overweight by any stretch. Alyssa spun around and looked at her butt, clad in the satin "Mother's Plus Collection" panties.
"Damn, I'm a hot mom!" She said, in disbelief.