What was your diagnosis process like?

I met with my PCP yesterday (she's a DO) to discuss the possibility of POTS. I quit caffeine early January, felt awful for months, then was diagnosed with fibromyalgia back in April (which I've suspected my whole adult life). I have still felt mostly awful, and realized symptoms I used to associate with caffeine withdrawal were clearly something else. I did multiple poor-mans tilt table tests at home and sent my numbers to my doctor ahead of my appointment. She definitely wants me to do more formal in-clinic testing, but she warned me that pursuing an official POTS diagnosis is extremely difficult. I'm not sure if what she was saying is based on the lack of specialists in our area or if this is just in general. I'm curious to hear others' experiences so I can have realistic expectations.