A heart monitor is a good start. Hopefully it is all clear for you. I have done a 24 hour monitor and a 5 day event monitor. Both showed nothing but a little tachycardia even when I can feel PVC's and PAC's they don't show upon the monitor. (Or so it's all in my head) I think the worst all day long as well. Literally, as if something else in controlling my thoughts. I read a book over the summer called The Power of Now by Eckhart Tolle. It was a really good book on how to distract your thoughts from running around and get them back to the present moment. I wake up lightheaded almost every single day from this anxiety. It's so hard to believe all of these symptoms are just anxiety related, I know. I especially have horrible vertigo, my husband often sees me stumble sideways into walls
luckily for me he laughs it off and makes uplifting comments so that I don't freak out about it. When I do have a good, non dizzy day, I try to make the very best of them. So far I've had 2 in an entire month
As far as the journal goes, my neurologist suggested this to me, to see if there is a pattern that may be hormone related as hormones are a nasty thing as well, that can bring on terrible anxiety and panic. You can print a blank calendar from google and just start marking the days every day before bed with a 1-10 number on how bad your symptoms were that day, then circle the first day of your period in red, so you know your cycle. Do it for a few months and bring it in to your next appointment. It may or may not have some glimmer of answer for you. For me, so far there is no real pattern on my calendar. Which confirms that it is simply the anxiety demon within trying to take over my life.