If you have ITP (I do too), then you should have a hematologist in case your platelets crash. A regular GP doesn't have the experience to handle it. They can prescribe Prednisone, but that's no good long term. There are so many more options. When I crash, I get the N-Plate shot. Only my hema could give me that.
I also have hemolytic anemia, which is like ITP for red blood cells. I developed this years after the ITP, so yes, so people develop other immune issues, but some don't.
And. White blood cell counts can swing wildly depending on what's going on - and it doesn't necessarily mean there's anything else wrong with you - it could just be a weird thing.
But it will be a good thing to have a hema. They won't bite you!