should i tell her? or just pretend it never happened
Don't tell her, just stop messing up her panty drawer. Find the ones she's already worn and wear those.
That means that she will have stains on her worn panties.
Is it normal to sniff her panties before I put them on?
Your just a horney kid in need of a girlfriend but until then.... well what's that saying, "any port in a storm." In the mean time I have to ask; are you like really stupid or something? I mean how hard is it to snatch a pair without messing up her drawer? Sounds like you want to be caught.
I am not the original poster, but I wore my sister's panties and and after awhile, I purposely let her catch me to see what she would do. She made me kiss every inch of her bum and she spanked me. You know what? I still let her catch me wearing her panties.