First it depends on how long you have tried a protocol and the compliance level before you consider changing things, as well as what the problem is. Some things resolve quickly, other can the a very long time.
Is it possible that the anxiety is actually stemming from a depressive state? There is mixed depressive-anxiety disorder, where you have both conditions.
I think I may need to focus on helping treat her with moderate depression as well as ADD. Both depression and anxiety are common co-morbidities of ADHD.
I would avoid large amounts of Lemon Balm with hypothyroid conditions, small amounts are not an issue, it is indicted for mild depression, so a tea with Mimosa flower (1-2 parts), Linden Flower (2 parts), Lemon Balm (1 part), Lavender (1/4 part) or something like that might be useful.
While the TSH is slightly above optimal, it is not indicating nor the other thyroid values thyroid dysfunction. it could suggest low levels of Iodine, Selenium or zinc.