I am 25 one side of tonsils and adenoids atrophied while the other remains enlarged. Without pain or hoarseness. Do tonsils and adenoids atrophy bilaterally at the same time?

May be. Asymmetric enlargement of tonsils are common. However, lymphoma as the cause of unilateral tonsil enlargement does happen in young healthy people. See an ENT doctor!
Tonsils and adenoids. Hello, it is quite common to see the lymph tissues in the tonsil/adenoids area atrophy at different rates. If you feel it looks significantly different then see your ENT doctor. Regardless, bring it to your family doctor's attention at your next appointment.