It does sound like Hypothyroidism. Have you had her tested?
Check the lab report to see if there's an adjustment for age. Babies often run higher TSH levels than adults. Are the T3 and T4 results for Free or Total? They are not the same. Also, what are the reference ranges for those? Ranges vary lab to lab, so have to come from ones own report.
Does she exhibit symptoms of being hypo? If so, which ones.