I'm glad you got Meg tested and are able to get treatment for her, it is so easy to miss, well done your Auntie!
I'm sure she will soon feel great on her meds, I hope they kick in soon and you have a happy, bouncy girl again.
I'm actually going to have Tia tested, I'd asked the vets I work with, way back last year after I got her, if she could have this, and they said no as she has a good coat, but she does have all the other symptoms - can't lose weight, always tired, lags behind on walks a lot, and generally acts like a dog much much older than 5.
Thanks for posting this Emma, I'm sure there will be many people who recognise the same symptoms in their dogs.