With your CBC,
thyroid,
sugar, inflammation markers and ultrasound all coming back normal, anxiety or a quiet shift in your eating, sleep or activity is a common explanation for unexplained weight loss. It isn't the only possibility though.
Next Steps
Track your actual food intake and weight weekly for a month, and tell your physician about any stress, low mood or appetite changes you've noticed. If the weight keeps dropping despite these normal results, further checks such as a stool test or chest X-ray can help rule out other causes.
Health Tips
See your doctor in person if the weight loss continues, since repeated normal tests don't rule out every cause.