Sounds like you're onto something, associating the anxiety with the weight loss. You got me wondering 'Does anxiety speed up metabolism' (which I typed into the search engine). Apparently it does. You then got me wondering 'Does menstruation speed up metabolism'. Apparently it does. Sounds like you know yourself pretty well based on the things or links you're wondering about. The fact that you've changed your diet to a more natural one points to the fact you're a natural in a lot of ways.
While I enjoy researching biological and psychological factors in life, my number one love involves the natural and energetic aspects of self. May sound a little strange but do you find you're sensitive to rises in energy? Certain thoughts work you up, certain foods work you up, certain changes in body chemistry (such as with your cycles) work you up? What about sensory stimulation? Are you sensitive to certain sounds for example? In this case, sound gets you worked up. With a worked up metabolism and a worked up nervous system, we can be feeling pretty worked up. By the way, nothing quiet like ramping up a few good tunes to get us feeling pumped.
Balancing things out with what calms us down is pretty important, such as that change in diet you mention (a lot less harmful chemical reactions between food and your body). Meditation is an interesting one. Plenty of people will suggest meditation to others but it's key to know what your meditating on. We can meditate on a lot of things but if we're not meditating on the thing that will make the difference, it can feel like a pretty unproductive exercise. I'm sure there are guided meditations out there that focus on specifically calming the nervous system. This might be one for you. Me, I love to meditate on finding answers to what I wonder about. In other words, I zone out and let the answers come to me. Great way to exercise our intuition by the way. I've been accused of being a serious daydreamer at times :)
With the bowel issues, there's a lot of research being done these days under the title of 'Mood and Food'. Imbalances in the gut can not only contribute to our questionable toilet habits, experts are now discovering the relationship between gut imbalances and anxiety and depression. It's interesting stuff.
Definitely sounds like you're a natural, on track to knowing yourself better. As you go along, you'll naturally come to know what you're super sensitive to. Before you know it, you'll be super natural.