To be terrified about my daughter's thyroid

[Greengreengrassss]

My daughter is 7 and her TSH levels have been creeping up for a few years now. The most recent result has come back at 10. Her T3 and T4 are normal but she does have thyroid antibodies.
Her paediatrician has sought advice from endocrinology and they've said she doesn't need treatment unless her levels go above 20 but want to have repeat tests to keep an eye on it.
She has a genetic condition and her auntie, grandma and great grandma all have an underactive thyroid.
I don't want her to end up on medication for the rest of her life and dealing with symptoms.
My understanding is that her pituitary gland is working over time to keep the T4 and T3 levels normal because the antibodies are attacking it.
I feel like it's only a matter of time before things start to go downhill.
I just feel so sad for her. She's faced so many challenges and overcome them but I feel as though the odds are against her.
Am I being silly? Does anyone have any experience of this, especially in children? Is my understanding correct?

That’s really good to know. Thank you! She comes downstairs and really struggles to straighten her legs! She’s all hunched over like a really old lady! Hopefully the medication will help!

Did your leg pain get worse before it got better? My daughter is really struggling today with pain in her legs and now also her knees. She only started the meds on Tuesday but already feels like they're making her feel worse!

The meds take about a month to start working, it's likely she's feeling worse because of the cold as it slows thyroid function down more. I reckon another couple of weeks and she'll start to feel better...fingers crossed!!