v Just because someone works at a shop doesn't mean they actually know what they're talking about. There are a lot of hacks out there who get the title of "professional" simply because they work in a shop, and that really means nothing. I once had a "professional" piercer tell me that it was perfectly fine to use Neosporin on a new piercing (which is something that everyone knows is just the most idiotic thing you can do to a new piercing), and another that shoved a 00g taper through a friend's ears when they were at 10g before - also something that is incredibly stupid and should never be done. (And I'd be suspicious of any piercing who is gung-ho about giving stretching advice to someone your age, anyway. Which I don't say to offend, it's just...not right.)
If it hurts, you're doing it wrong. That's all there is to it. You should never "just shove it through." If it doesn't fit, it's fine to try to nudge it just a little bit and let it settle, but you should never have to "just shove" it.
Jinxeh I know what I'm doing. I followed the piercing guy's "instructions" and I'm aware that I'm stretching my ears at just 13. Trust me, I know what I'm getting myself into.
1.) The general rule of stretching your ears is "If it hurts, you're doing it wrong." So yeah, I'd say you're doing it wrong.
2.) Learn the size system. You don't go from 2 to 3; you can go from 2g to 1g, but generally it's 2g to 0g. If you don't know what you're doing, and you have no idea what you're shoving through your ears, just don't do it. Wikipedia has a chart here, though: http://tinyurl.com/yh7r4ql In case you're curious as to how the sizes actually work.
3.) You're thirteen. Do you really think you should be stretching your ears right now? Especially when you probably don't have the money to invest in the proper jewelry and care?
4.) Just remember - stretching your ears is a body modification that should be taken as seriously as piercings and tattoos. After a certain point, it's permanent. Don't do this if you don't think for sure that it'll be what you want ten, twenty, thirty years from now.