She's thin but I'm not sure about too thin. She may still be breast feeding and when I was, my weight was at its lowest no matter how much I ate. Like it or not, she must feel under huge pressure to lose the baby weight being in the public eye, unlike Zara Phillips who appears not to give a damn. Anyway- better to be too thin than too fat like most of the UK! Unless she has an eating disorder, being thin is not harmful, unless it's taken to extreme.
The work on her teeth was well documented ages back- she's had lingual braces (at the back of teeth) and supposedly chose to have an imperfect natural smile, keeping a gap between her front teeth. She hasn't had veneers but may have carried on with the braces.
Doubt very much if she has had tattooed eyeliner- there for good as an ageing queen?
I don't think it matters a jot that she went to uni and hasn't used her degree- same happens to thousands of 'normal' people. She isn't obliged to have a high flying career any more I suspect than most people posting here. I'd rather have a normal life and a job than have her role - living in a goldfish bowl and on duty for the rest of my days, no matter how much money I had for fripperies or holidays.