Seems like you got some good signs that it was her 
Here’s a guide on how to scan, this is tailored towards people scanning people on this forum, but you can adapt it to scanning her energy when you evoke her:
For your situation, next time you try and evoke her/interact with her. Focus your mind on her energy (if you feel her presence, focus on what that presence feels like – images might come to your mind, emotions, sensations, feelings – all ways that your mind might interpret her energy). It could help to try and connect your 3rd eye, but honestly I just focus my attention on whatever I’m trying to scan. If you can’t sense her presence, then next time…scan your surroundings and see if anything comes up - then you might be able to sense her.
Another way to think of scanning, is about shifting to where your awareness is. Your awareness is where your consciousness is focused. Or your attention. Energy follows awareness. So next time you evoke, change your awareness to her from whatever ritual your doing.
Scanning is useful because it can help to verify what/who an entity is and to get information about that entity. Plus it can also help with communication, since information through communication can come through the same type of ways that it does during a scan (mental images, impressions, thoughts that don’t seem like your own, emotions, etc). It’ll be subtle at first but keep going. Follow your gut instinct, you seem like your pretty sure it was Freya – so trust that