But I thought she met Malcolm before leaving Raith.
I don't think so.
The "official" timeline (crowdsourced as a fanwork largely here on the Paranet, but embraced by Jim & blessed as official on his site) lists them close together, but with her escaping Raith coming separately, and prior to, her meeting Malcolm Dresden. For reference, her giving Thomas his copy of the pentacle amulet happened before she left, but not as a separate entry.
I'm also almost certain I recall a WoJ clarifying that yes, she had already left Raith when she met Dresden, tho I cannot search for it now.