Nah, no one is stupid, just inexperience

Anyway, what you can do now is just handle Geri nicely, let her get used to your hand going in and out of her tank. Pick her up with your hands, that's the best way to let Geri recognize your smell and warmth.

Don't be scared of your gerbil, animals can sense fear. Be confident with Geri.

You can get Geri a tankmate later, but it would be safer if you purchase another young girl gerbil, so territorial matters do not come about. Gerbils can be a bit fierce when it comes to space, so introducing them in the right way is crucial. Hope your mom doesn't mind you having another gerbil