How far should you put a tampon applicator in?

I've asked many "computerized" websites and they all say well you tampons probably not in far enough! I really want someone who actually has their period and knows! I can always feel my tampon especially when I bend over it feels as if it was "sliding" out. So I always try to stick it in farther but it just hurts! I want an answer in about inches please! Thank you in advance!!!