Also -- This subconsciously using paleo to restrict yourself from gaining I can relate to as well. I went on a crash diet, that was ketosis based, this past winter. Lost 20 lbs. I was at 121 lbs. I have since gained 13 of that back. I have never really had issues with food. I have had issues with my body, but not really eating. After this diet, I had such guilt around eating, eating anything. I would decide just to enjoy a meal and then wake up a pound heavier and feel such guilt. I felt paralyzed to do anything about it. I would restrict my calories that day, go to the gym, make myself miserable.
I came across Primal and started to see a light at the end of the tunnel. I've done a ton of research on eating and body fat gains and loses, trying to figure out what will work for me. I am not really there yet. But one thing I realized is that paleo is not about what I look like, it's about health as you said.
Today I am primal and low carb, plus I drink probably 3 days a week (I am social). I crossfit twice a week and I am tweaking as I go. I haven't been feeling great lately and I believe it's be cause I need more carbs in my diet.
Here is my point, I haven't totally figured it out. I seem to be gaining weight and not losing. But I have made a decision to shift my focus from "my ass is too big and my stomach sticks out here" to "I am doing this to be healthy and to be strong." I am learning to love the body I have and realize that being 10lbs lighter won't magically change my life (you know hot boyfriend, lots of money, lol). I don't allow myself to negative talk when I look in the mirror. Instead I say "Nice T&A" (hey, if you don't have anything nice to say...).
I think that might help you with some of the anxiety you feel around gaining weight. I lost my period at 124-121 lbs for 4 mos, so I know I was anything but healthy. I needed to put some fat back on.
I've been listening to Everyday Paleo podcasts: Podcasts | Everyday Paleo Lifestyle and Fitness I HIGHLY recommend you do the same. They talk a lot about ascetic goals and how people (mostly women) tend to fail when they focus on ascetics. Basically, you can't fix what you hate. So try loving the body you have, go back to the diet you felt good on and maybe work on the stress levels to fix the sleeping issues. I also recommend a magnesium supplement for help sleeping.
If all else fails I remind myself that men think we all weight about 10 lbs less then we actually do! Good Luck, feel better.
Oh and yeah, I agree go see a doctor.