I have not been diagnosed with hypothyroidism but have the symptoms, yet my tsh dropped from 2.69 to 1.78 in 8 months. what are the explanations?

TSH : Levels of TSH vary naturally. Small changes within normal range do not necessarily mean that it is a trend, i.e. Continue to drop. Your symptoms might not be related to thyroid. Normal level of TSH alone cannot rule out thyroid disease. See your physician for further workup.

Both normal: Tsh levels can vary within a certain range from day to day depending on the body's thyroid requirement. Both are normal. This is not an issue.

Normal TSH: Both TSH values are within normal limits. The absolute values may vary within the normal range as a result of many factors, including time of day, nutrition, menstrual status, and lab variance. I would look for other causes for your symptoms.

Both normal but: If you still have symptoms such as fatigue, constipation, dry skin, dry hair, etc. I suggest having your doctor check your free t3, (liothyronine) free T4 and reverse T3 (liothyronine) levels. Sometimes your TSH is normal but your body is not converting the inactive T4 to free T3 (liothyronine) or converting it to reverse T3 (liothyronine) which is inactive but TSH is still normal. If those are normal, then look into other causes.