Ask her if she morphs into your younger mom again.

"So um... mom, I don't know if you want to, um... can you morphs yourself younger like me again, like you did before when we have sex?" you asks awkwardly.

"Of course, sweetie. There's always the thing 'mommy' can do for her 'son'." your shapeshifting girlfriend/mom answers as you looked at your girlfriend/mom as she quickly starts shrinking down and making herself younger once more. First, her face has less and fainter wrinkles, making her way more younger and prettier, as for her hair got straight and smoother. And then, the skin of her body are getting tighter and smoother than before, also she's getting thinner too. After that, her breasts which were double size of F-cups are now shrinking into double DD-cups. Finally, when the transformation is complete, your transformed girlfriend/mom has reached at the same age as yours once again. You're thinking she look a lot like your sister identical twin. "So, sweetie. Do you like it?" she asks with her younger voice.

"Yes, 'mom'. I do." you blush.

"Teehee, why are you so red, sweetie?" your girlfriend/mother asks.

"Be...because I... well... you look pretty cute when you're younger, 'mom'." you answer awkwardly as your girlfriend/mom giggles.

"Aww, thank you, sweetie." your shapeshifting girlfriend/mom says as she admires you when you said she's cute. "And come to think of it, you really prefer the 'younger me' more than 'my older self', don't you?"

"Well, n...no... you look so beautiful in your older form, it's just that I just want to try something news, 'mom'." you answer panicly.

"Teehee, it's okay, sweetie. I'm just teasing you." your girlfriend/mom says as she teases you and you sign. "And y'know, sweetie, if you want me to change into somebody else, you could ask 'mommy', because I do this for my wealthy handsome 'son'."

"Thank, 'mom'." you finish your word as you then give her a kiss on the lips.

"So sweetie, what do you want to do next?" your girlfriend/mom asks when she broke the kiss.