I don't know that I'm going to be much help because I'm so much older than you are, but I've lived in those shoes all my life. And you're right, there aren't too many people to talk to about this, because nobody wants to hear the complaints of someone under 100lbs. On the other hand, I know several very thin women around here and, while they may not talk about this, I know it's a preoccupation for them. It's been so ever since the fashion industry made "tiny" beautiful.
I have a pair of shorts that a girlfriend passed to me when I was 17 because she couldn't get into them, and every year I take them out ceremonially to see if I can still get into them. This is the first year I cannot, and I am having a LOT of anxiety about it. I am very tiny and small-boned to start with - generally without dieting, excessive exercise or being "too thin", and have never considered myself anorexic. Still, being thin has been a huge part of my self-concept, and staying thin has, at times, been a preoccupation.
Now I'm in perimenopause, and my body is doing what women's bodies my age do - putting on weight. I'm fighting like a dog to stay under 100, and it takes a toll on my psyche.
I guess the one thing I did was to make sure I had extremely good nutrition. If you're not sure about healthy eating, learning would be my first priority. There's an excellent web site I've discovered called "World's Healthiest Foods," and it is a great educator on nutrition. It's at http://www.whfoods.com/. The second thing is sleep, since you mention your energy level. I think everyone has a minimum number of hours that leaves you feeling best, and once you figure that out, you should do your level best to make sure you get it.
On the good side, honestly - I am extremely healthy for my age. My own doctor can't believe my age. She attributes it to staying thin and very healthy eating.
If you ever want to talk about this, feel free to contact me.