Sounds like you have several of the same issues I'm recovering from. Here are some recommendations based on what has helped me.
Your first line of attack should be consistent, high-calorie, high-fat AND high-carbohydrate eating. Sounds like you've been mostly low-carb. If you have trouble gaining weight and have cold hands and feet, I think low-carb is your cause and definitely not your solution. Eating lots of starch (and lots of everything else) at every meal makes me so warm I sometimes have to remove layers of clothing during meals. (I used to have ice cold hands.) And it's the only way I can keep weight on, even when I'm totally sedentary.
The only time I have trouble sleeping is when I eat too much protein at dinner. Protein increases alertness by raising catecholamines. You really don't want too much of these before bedtime. I don't think it's any coincidence that the only time in my life when I would wake up night after night after night was during my four month low-carb experiment. Since switching to high-carb (which does not mean low-fat!) I've been sleeping effortlessly. Emphasize fat and carbs over protein at night and I would expect you'll notice a difference.
I have seen improvements in my constipation and skin issues lately with the recent addition of the following to my high-fat, high-carb diet:
- Gelatin mixed in with my meat and vegetables at every meal
- Raw greens, herbs, and a piece of fruit with every meal
- More fermented foods
- A little more water
- Daily walking and push-ups
- Daily use of transdermal magnesium oil (Swanson Ultra brand) and sometimes oregano oil (Natural Factors brand)
I couldn't say whether all of these help individually, but none should hurt, and together, they seem to be gradually helping me through a plateau I've been stuck in for a long time. I also use a ton of celtic sea salt at every meal, and I've noticed that my bowels seem a lot more sluggish without it.
Hope this gives you some ideas and good luck!