Posted 10/9/2019 5:15 PM (GMT -7)
It's unlikely, based on your symptoms, to be "just depression." Some medical doctors are, in my opinion, overly quick to suggest this because they don't know what exactly to diagnose you with and they (probably mistakenly) believe they can solve depression with medications. They prefer simple diagnoses, and things that can be demonstrated on blood tests. I went to at least three MDs who suggested my issues were "caused" by depression or anxiety before I found one who was awesome, actually listened when I described my many "small" symptoms, and was aware of recent research on the legitimacy of CFS/Fibro/this sort of thing (even though its still not easy to diagnose). (Depression and anxiety do, for some obvious reasons and maybe also unknown ones, frequently co-occur with conditions like Chronic Fatigue. That doesn't mean they cause them.)
Depression absolutely does cause fatigue, and can be very severe, of course. But on its own, it doesn't cause irregular heartbeats. Or dizziness or headaches, unless perhaps severe depression has lead to such limited physical activity that there's been severe deconditioning... beside the point.
My best suggestion is to keep visiting different doctors (as long as your insurance is able to cover this) until you find someone who you trust to listen to you. Your therapist may also be helpful in talking through the emotions and frustrations inevitable in that search. (E.g., I totally agree with you that gender dynamics can cause some patients to be "written off" too quickly, especially with behavioral diagnoses. There's a good body of research to show that this kind of bias frequently impedes women from accessing care, though I'm sure people of all genders suffer for it.)
I notice you posted this quite a while ago, so I hope you've had better luck since in seeking a diagnosis. CFS, along with many other things, may not be necessarily a "helpful" diagnosis in that there aren't cures or even clear treatments, but being able to validate your sense that these symptoms aren't just "all in your head" is a worthwhile pursuit. (Not at all to downplay the potential severity+realness of depression, which is itself more than "in one's head," but to suggest that you follow your intuition about what's really causing any issues you may be having.)
Note: I also saw an ND and other alternative practitioners that weren't necessarily helpful to me. My current excellent doctor is an MD. But some people do report better luck addressing these kinds of "diffuse" symptoms with doctors that have different training or more specialized training than your average Internal Medicine MD.