As it has already been explained to you, different noises bother different people in different ways we all have different ranges, et cetera
My dad was a loud snorer, a bit of a sonic boom, and occasionally kept me awake but not often, my mum sometimes snored and when she did it definitely kept me awake, aren't you? It wasn't as loud as my dad, but it was a different pitch and that just kept me awake.
Stop saying 'she's wrong it can't be me. I sleep downstairs. My door is shut'
unless for some reason, you are accusing her of stirring up Trouble, then accept you are keeping her awake and take whatever action you are prepared to, to stop it. There are a few new very soft mouthguard being advertised to stop snoring that look very soft light and comfortable it might be worth trying one of those.
It doesn't make any difference what time she goes to sleep or what she does before she goes to sleep if it's your snoring that's keeping her awake when she wants to sleep that's the issue.
Either deal with the issue or tell her tough, it might be time to move out. Your choice.