There is a really good cookbook that I've found which is all gluten and dairy free, called Cooking for Isaiah, by Silvana Nardone. It was written for her son who has dairy and gluten intolerance. I've tried tons of her recipes and they are yummy! Best Chocolate chip cookie recipe I've found so far also the best doughnuts I've had gluten free. Also, she has a blog if you do not want to buy the book, In Silvana's Kitchen.
Have you had all of your vitamin levels checked? Many vitamin deficiencies can cause constipation. I was severely constipated for several months when I had never had any issues before...in fact I always had the opposite issue. After checking my levels it turned out I was B12 deficient. Since starting treatment I am back to normal. Hope you find something that works. Constipation is miserable.
Also, just saw in your post about your anxiety which can also be a symptom of low B12. I found myself panicking and having insomnia and had no clue of why. I had never been an anxious person before the low B12.