My dog hasn't peed for 16 hours

She went last night before bed but now it's the afternoon and she just won't go. She's not straining without producing and she doesn't seem to be in pain, but she's been eating and drinking normally so there's no way she doesn't have to go.

I watched a bunch of videos and I've tried a million times to express her bladder but clearly I'm doing something wrong. Is it time for the emergency vet or should I wait until the 24-hour mark? Any tips on how to get her to just go?