I'm seeing a girl for a prospective matrimonial partner. She is 27 with a height of 5?3? and weight 55 kg. She reported that she has ongoing medication of thyroxine 25 mcg for subclinical thyroid. I want to know how critical is this illness. Whether it has some serious symptoms, and implications and is curable or not. Are there implications for pregnancy complications or possibility of pass it to the child?

she said her hypothyroidism was diagnosed when she had a bit of weight gain and hair fall a couple of years back with tsh levels of 8miu/l. Does tsh levels of 8miu/l indicate subclinical hypothyroidism? Some articles online suggest tsh 8mlu/l as overt hypothyroidism and not subclinical. After that doctor suggested thyroxine 25 mcg. Now her tsh is around 2.5miu/l with the medication. 

also, her mother is suffering from hypothyroidism. Is there anything to worry about? Can she live a healthy life with ongoing medication? Are there any dietary restrictions for this or does any other care need to be taken apart from the medication?