So we have enough for leveling? Hmm... no idea what to do. I could take another level of Rogue, but no idea what archetype. Since she can't see worth a damn in the darkness, Assassin doesn't seem like a good idea. Arcane Trickster might be useful, but the good illusion spells that would really help don't come online for several levels. Thief wouldn't be too bad, maybe.
Or I could multiclass. The original Whisper character concept was to go Monk (Way of the Shadow). I wasn't going to pursue it here because I doubted she would live long enough for it to matter. Had I started her out as a monk, she could cast Darkvision now
Monk 1 would boost her AC a little. I'll have to think about it when I get home.