Hi Jamie, Welcome here. And don't worry, you're not "bothering" anyone, I'm sure.

Anyway, just a thought. You never mentioned rats, have you tried feeding her rats instead of mice? She could just be a weird one. There is no way of knowing for sure if she is pregnant or not unless you begin to notice she lay "inverted" or "upside down" (belly up). This does usually mean she has ovulated, and is gravid. But I would doubt it if you haven't witnessed any copulation.

Get back to me.
Jennifer