When you start taking thyroid med, your TSH goes down in response. The lower TSH provides less stimulation to your thyroid gland, so less natural thyroid is produced. The end result of this is that a patient ends up needing a full daily replacement amount of thyroid hormone med.
You are taking 100 mcg of T4 only 5 days a week. That is not a full replacement amount, as evidenced by your low Free T4 test result. I cannot understand how you have no hypothyroid symptoms taking that dosage; however, as they say, "If it isn't broken, don't fix it". So I would not be concerned further unless you start to notice hypothyroid symptoms.
Your Free T4 is below range. The Free T3 does not show a range, but I expect that the result is somewhat close to mid-range. For many people those results would be too low to avoid hypothyroid symptoms. As long as you do not have hypothyroid symptoms I see nothing to be concerned about. If you should start having hypo symptoms, then you would need to increase your daily dosage of Levothyroxine, which you have not told us about yet.
You showed test results for only TSH and Free T4. As I mentioned, TSH is useless as a diagnostic of thyroid status, when already taking thyroid med. Your Free T4 was only 22% of its range, which is typically too low, unless Free T3 is in the high end of its range. But it appears that you were not even tested for Free T3.
What is your daily dose of levothyroxine?
A comprehensive definition of hypothyroidism is "insufficient T3 genomic effect in tissue throughout the body due to inadequate supply of, or response to, the hormones". The main thyroid hormones are Free T4 an Free T3. Free T3 creates the metabolic activity in your body's cells. Free T4 must be converted to Free T3 in order to be used. So you need to know Free T3 levels along with Free T4. TSH has only a weak correlation with the thyroid hormones, and has a negligible correlation with hypothyroid symptoms, which are the hypo patient's main concern. So TSH is useful only when at extreme levels indicating primary, overt hypothyroidism such as Hashimoto's Thyroiditis. After such a diagnosis, TSH has no further value as a diagnostic, and should never be used to determine a hypo patient's med dosage.
Only testing your TSH and FT4 is inadequate. You should always be tested for Free T3 also. As mentioned it is also important to test for Vitamin D, B12 and ferritin and then supplement as needed to relieve hypo symptoms. The only concern with Hashi's is the effect of the antibodies attacking and eventually destroying your thyroid gland, and associated loss of production of natural thyroid hormone. That loss of natural thyroid must be fully replaced with thyroid medication, or symptoms occur. Speaking of symptoms, it is hard to imagine you not having symptoms. There are a wide variety of hypothyroid symptoms, but
please have a look at this list of typical hypothyroid symptoms and tell us which, if any, you have.
Increased sensitivity to cold
Constipation (have to use laxatives or fiber)
Dry skin (you use skin creme)
Weight gain ( and difficult to lose weight)
Elevated blood cholesterol level
Muscle aches, tenderness and stiffness
Pain, stiffness or swelling in your joints
Heavier than normal or irregular menstrual periods
Slowed heart rate
Enlarged thyroid gland (goiter)
One further question. What is your daily dosage of Levothyroxine?
You only become a "normal" person if your hypothyroidism is treated adequately to relieve your hypothyroid symptoms. Being on T4 med only, and being dosed based on getting TSH to a level that makes the doctor happy, it is unlikely that you are anywhere near being treated adequately.
The only time TSH is useful as a diagnostic is for primary overt hypothyroidism. All other types of hypothyroidism are overlooked when TSH is the determinant. When taking thyroid med, TSH should never be used to determine dosage. Have you been tested for the actual thyroid hormones Free T4 and Free T3? If so, please posts results and reference ranges shown on the lab report. if not tested for those, you need to get that done. Also, would be good to test for Vitamin D, B12 and ferritin. Those are important for you as well.
For diagnosis, symptoms are even more important than lab tests. So please tell us about symptoms you have.
If you want to confirm all this, please read my paper in the following link.