how can i tighten my skin

[N1kolai]

im 168 50kg and i always feel bloated especially from milk
im drinking 1l a day and ts bloats me hard so i reduced to 0.5
idk how i can tighen my skin
im 14 rn maybe it will change w puberty
hope so ngl
is there any way i can change that
pls help

 

[H72]

Masaii jumps

 

[Sxmon210]

idiot drink no milk then but ghk-cu does help