I've feel the same in the past, when it comes to real symptoms we need what I like to call "extra tools" these go beyond what you can mentally work with. The hard work it's finding your own tools and commit to them. For example, when I had these sort of panic attacks I felt safe in cold places, like the shower or the backyard, or with a chilled water glass, and then I would start breathing into 4's (inhale in 4s, maintain for 4s, exhale in 4s)
Other thing that helped me a lot was watching friendly cartoons, mostly Pingu in my case, and I know it sounds incredibly childish but it gave sooo much peace!
Again, this is what it worked for me, but the point is to find your own "safe place" so you can take all the time you need to calm down and realize that nothing bad is happening.
I hope you can feel better until your appt. Remember that there is no need to rush to be ok, take your time, don't push yourself, and know that you'll find support here :)