I did pumping in the past using the bathmate for at least 3 months non stop with no stretches or manual exercises and made no gains. Very depressing.
That’s why I added stretches and hanging to contribute with my pumping.
Giethbwork takes time to bring result that's why it is good to wait for at least 6 months before measuring. You didn't gain girth because you weren't doing any manual girth exercises in between pumping sets.