I'm afraid that somebody lied to you. You have all the classic symptoms of Gilbert's Syndrome.
There is an outstanding website dedicated to GS Symptoms, and weight loss is frequently mentioned: Search this document for all the occurrences of "WEIGHT" Hold the CTRL key Plus the F key and enter weight into your search term: http://www.gilbertssyndrome.com/symptoms.php
Also search this doc for your other symptoms.