TSH is a pituitary hormone that doctors like to believe accurately reflects actual thyroid hormone levels. It does not. Except at extreme levels TSH has only a weak correlation with a person's FT4 and FT3 levels and a negligible correlation with the person's actual thyroid status. So since you have the actual Free T4 and Free T3 test results, it is more useful to assess those. To do that we need to know the reference ranges shown on the lab report, or used by the doctor to assess results.
When I look at pediatric reference ranges for TSH it shows for 1-12 months a range of 1.12 - 8.21. For 1-5 years the range is .80 - 6.26. So in consideration of that, and the variability in TSH results I mentioned, I see nothing there to be concerned about. If the TSH is indicative of an autoimmune disorder called Hashimoto's Thyroiditis, then it would show in the TPO ab and TG ab tests. Was there a range given for those?
Looking at her Free T4 of 1.2 and her Free T3 of 5.3 compared to those ranges, there is noting there that stands out as a problem. In adult patients an evaluation for symptoms that occur more frequently with hypothyroidism is more important than biochemical tests. Note the following I found in an site on pediatric thyroid ranges. and keep it in mind
"It's of utmost importance to assess signs and symptoms of hypothyroidism in infants and children in addition to lab results when determining their thyroid hormone status and whether thyroid hormone supplementation is warranted or not. Those signs and symptoms include:
Thick, protruding tongue
Dry, brittle hair
Low muscle tone (floppy infant)
Hoarse-sounding cry or voice
Short arms and legs
Very large soft spots on the skull (fontanelles)
Wide hands with short fingers
Thyroid antibodies should always be checked when assessing thyroid status given the high prevalence of autoimmune induced hypothyroidism. Naturally, these antibodies ideally should be as low as possible. Once again reference ranges vary widely from lab to lab. The Endocrine Society has determined the reference range for thyroid antibodies to be:
TPO (Thyroperoxidase) - < 2.0 IU/mL
TgAb (Thyroglobulin antibodies) - < 4.0 IU/mL"
Pediatric reference ranges for thyroid tests are often debatable. From your daughter's FT4 and FT3 results I see nothing of concern there. If there is anything at all in your daughter's test results that warrant a further discussion with the doctor it would be her TSH and TPO ab results. From that discussion you should be able to determine why the doctor even mentioned seeing an Endo.