Hypothyroid, fatigue

Your son will get the best responses from treatment by working directly with an acupuncturist who also practices Chinese Medicine.  The herbs you chose for him seem to be mostly unrelated, in my mind at least, to the issues you are describing.  Si Jun Zi Tang is more for deep qi deficiency which he doesn't seem to have (ie he plays sports, eats and digests well, etc.) and Xiang Sha Liu Jun Zi Tang is again more for qi deficiency, which doesn't seem related.  If your son feels good most of the time, is active, can play sports well and digests his food well and has regular bowel movements, etc. it may just be that he doesn't get good sleep at night and needs to catch up which may or may not be ok.  Or he really does tap out (kidney deficiency yin, yang or both).  Does he seem to feel he has a problem?  or is he comfortable with the flow of his life and his general energy levels?

One thing to check with the thyroid, if you haven't already, is the thyroid peroxidase antibody test - I've seen clinically where, at least for a period of years, people may test normal on the base thyroid exams, but their autoimmune antibodies (ie their body attacking their thyroid) levels are high.  What you do about that would vary widely, but it would be good to at least pull those autoimmune related tests every couple years even if their clinical value is debatable.

For treatment, again, I would strongly recommend finding a well rounded Chinese Medicine practitioner and work with him/her over a period of at least 6 months.  But generally, you would either try to consider improving the quality of sleep (this could be meditation, other sleep/lifestyle practices - less night screen time, etc.) - possibly something as basic as oyster shells (pearl powder) or more mild formulas (that would depend on his diagnosis from a practitioner in TCM terms) - tian wang bu xin wan for mild heart/kidney yin deficiency or an shen bu xin wan for mild yin/heart blood deficiency -- both fall into the "calm the spirit" category in tcm terms.  Or you might consider moving more towards kidney yin (or yang, again depending on the diagnosis) tonics (not more general qi tonics like you have tried).  A main formula for kidney/liver yin is liu wei di huang wan and a main formula for kidney yang would be jin gui shen qi wan.  

There are a host of factors that would steer a practitioner towards one direction or another and with younger patients this gets even more complicated.  Further a practitioner who practices both acupuncture and herbal medicine may for reasons of clinical experience or even safety choose to handle/support some aspects more with acupuncture and/or moxibustion, others more with diet/lifestyle, and other aspects with herbs.  Chinese Medicine can be really helpful in situations like this, but not only is it complicated it also, often, takes time - on the order of months at least, not weeks or days to see some of the responses you may be expecting.  Part of this is the practitioner working to find what the body is needing - ie what the root imbalance is that is behind the symptoms.