In terms of the rash decision you made it was one of the better ones. While your concept of "self" was merging a bit too closely with your mother you did understand that the chronivac could change things back, but you didn't feel like getting into a tussle with your brother even if you fully changed yourself back to normal. So as your mother's memory saw your brother as her little baby you set Ben's age to 1 year old quickly and hit enter.
Your little brother on the floor tried to get up as he put his right arm on the ground and tried to push up, but found he couldn't as his arm shrunk faster than he could put force on the ground. He looked at his arms were small and pudgy as the rest of his body shrunk till he was in a pool of his own clothing. A few more keystrokes and you had put in some mental changes and altered reality to fit his change. You watched and saw your little brother in the puddle of his clothes disappear from your room as he was teleported back to his own room into his crib that was generated as his room turned into a nursery. You also presumed your actual mom's breasts had grown a bit and started lactating as your own were doing the same.
The moment of terror passed you stretched your back, took a deep breath, and thought that maybe it was about time to either nurse Ben or pump... Right... The Chronivac was still turning your mind into your moms, and she was having more and more influence. Working the Chronivac's controls you attempted to fix it...