Trudy44 Yes, it is difficult, certainly when we have to fight for ourselves but you have to fight on your daughter's behalf. So you need a plan of action and let the doctors know that you intend to learn all you can and do your best for your daughter so that she doesn't suffer unnecessarily.
Next time the endo says 'normal', get our a notebook and pen, tell her you are doing your best to learn all about this illness so you can help your daughter, that you want to document her progress so will she please give you the name of the test, the result and the reference range. If you don't have the previous figures, ask how the new results compare with the previous ones and write them all down.
Maybe you or your daughter can make a spreadsheet, put the date, time blood was drawn, test name, result, reference range, what dose of meds, how she felt. Update every time. This will be invaluable in the future if any change to dose of meds is suggested (thinking decrease here). You can look back and say..... 'when she was on XX dose of Levo her results were AA/BB and she felt quite good, had energy (whatever). Now you want to reduce her dose back down to YY dose of Levo but when she was on that before she was suffering ...(whatever)... it just doesn't make sense that you would want her to have a return of all those symptoms' ... sort of thing.
Read and learn all you can so that you can discuss with some knowledge. If necessary push for a free T3 test if the endo wants to reduce meds on TSH alone if it's low. We can only be over medicated if our FT3 (the active hormone) is over range, not if the TSH is low or the FT4 is top of range. Push also for antibodies to be tested, both types - thyroid peroxidase and thyroglobulin as TPO can be negative TG can be positive for autoimmune thyroiditis.
On her current results your daughter definitely needs an increase in Levo, the next step would be 100mcg then another test after 6 weeks, then an increase, repeat test in 6 weeks, etc until she gets that TSH down to where it needs to be for her to feel well.
She has an important year coming up with her exams, emphasise to the endo how important this is for her to feel well and to do well at school as her future relies on it.