Hi there, Queenofnothingatall,
Thanks for visiting the Apple Support Communities. If we understand, your Apple Watch has not automatically taken a resting heart rate reading in quite some time. We are happy to help!
Based on what you've described, we recommend using the information outlined in Get the most accurate measurements using your Apple Watch - Apple Support to ensure your watch has the right fit on your wrist and all the right settings to obtain as accurate a reading as possible. Even though the article talks about your active heart rate and readings during workouts, the settings and fit of your watch are important for gathering your resting heart rate as well.
You can get more information on how your Apple Watch monitors your heart rate here: Monitor your heart rate with Apple Watch - Apple Support.
Don't hesitate to repost back if you still need help.
Have a great rest of your weekend!