You had a stroke of inspiration but didn't have a chance to think in through fully. your mom was expecting a response. "Nothing so drastic mom. I made you a year older. I had noticed that things changed around me, did you finish high school in this reality?"
"Oh, yes, just barely." Mom said flustered. You were implying that she got pregnant at 16 with a 20 year old originally, claiming you made her 17 when you were born. The 11 year age difference between you and your sister made sense, you were an accident, she was planned.
"I want to look around at what's changed before you do something without me there." You walked around the house pointing out things that had changed, either claiming them to be better than before or just saying they are different. Your mom followed curious. Your age spurt without aging everyone made your conception 7 years earlier, before your parents finished college. and before your mother got out of high school.
The three bedroom house your family had, shrunk to a much smaller 2 bedroom 1 bathroom house, and the living room area was nothing compared to what you were used to. You subtly felt your pants pocket feeling a cell phone you never had before, keys, presumably for a car but maybe for your own house or apartment, you grabbed your wallet looking at your ID and manly face, showing your address being different than the one you grew up with, but it could still be this house for all you knew. With such a drastic change to reality, there is nothing to say you were even raised in the same town.
"There's something else I want to see." you said looking out at the road, noticing an old, beaten up Toyota in the driveway instead of the new SUV you remembered her having. "You were watching over my shoulder the first time I made changes, what if you were in the same room but not looking at the screen?"
You hurry back to the bathroom noticing for the first time that the laptop you were using was smaller and less powerful. "I'm going to make a change to myself, you tell me if you notice anything." you decrease your age by 3 years and wait for the program to apply the changes, your mom was unable to see the screen. As reality shifts you find yourself back in the office you were used to. The laptop is still an older and cheaper model but the house is better.
"Mom, do you notice anything different?" As she looks at you she tries but can't pinpoint what's changed. "Here, sit down" you give her the seat. "I've just come from a reality where I'm three years older and you were 1 year younger. Our lives were crappier and I realized it was because you didn't get a chance to finish high school, and you and dad didnt finish college before I was born. This fixed that and I'm willing to keep it this way. Go ahead, age me three years and watch what it does. There won't be room for me to be behind you if things happen like I expect, so I will stand in your position."
You stood there knowing full well that you set yourself up to become progressed to 21 and then regressed to 18. If all goes as planned, you will get new memories here and get to skip high school and go straight to adulthood. all you need is for her to click the buttons...