Alexa injected herself with her own chromosomes which she had combined with the significantly modified DNA of a T-rex.
Alexa took off all her clothes in front of a full length mirror so she could enjoy watching her transformation. A few minutes later she felt her body start to change.
Alexa watched her fingernails turn into claws, her legs became more muscular, her toes widen and compress into three clawed dinosaur feet. She looked down and watched both her feet then suddenly grow much bigger. She opened her mouth and watched her teeth become sharp and pointed. She turned around and looked in the mirror at her butt, watching it suddenly expand.
Her arousal went through the roof.
"Oh yes! Bigger!"
Alexa bit her lip and watched her butt expand a second time in the mirror.
"Yes! More!"
Alexa smacked her butt hard and watched it grow a third time. Then she watched her new tail poke out from the end of her spine and continue to grow along with her beautiful butt. Her hips grew wider. Her tail kept growing out more and more, forcing her to lean forward as her posture permanently changed. Her hair color changed from blond to white. Her eyes changed from blue to red and started glowing.
Alexa looked straight at herself in the mirror and let out her first sexy mighty rawr.
As she rawred into the mirror Alexa saw two C cup boobs suddenly expand out on her chest. She looked down in shock and grabbed her new breasts which had instantly become more sensitive.
"Oh yeah. Nathan is gonna love these."
In less than 20 minutes her transformation was over. Because of her new body shape she was now exactly 3 feet tall. She scanned her body in the mirror.
"Damn, I look good!"
Later on that day her boyfriend Nathan walked in.
"Surprise!" she said.
"Holy crap! You actually did it!" he said.
"I told you I could."
She held up her breasts.
"Check out these new awesome boobs I grew! What do you think of me now?" she said while wagging her tail.