How Many Reps Should I Do For Girth Gains

I have been working on girth doing squeeze.

(5 seconds of squeeze with slightly pushing forward and release, then I do it again until I reach to 10 reps. I do this 5 sets with the 30 seconds rest between the sets)

It has been 5 months and still no gains at all.

Is it not enough to get a gain?

How many reps do you usually did to get girth gains?

I do not want my son get longer since he got already long enough when I did jelqs for a year about 5 years ago and it makes my son look thinner and my partner does not like it for it strikes her womb, so only for girth.