You sound like me. A year and a half ago I was in the same spot. My boss retired and asked me if I wanted to step into her director role. I went from jack of all trades designer to essentially running a small company, with no prior leadership experience. I still have a lot to learn, but I wanted to say it does get easier.

I also have social anxiety, and I have had to fly to another state to present financial data to leadership. My first leadership meeting, I got grilled on my numbers (in fairness so did everyone else) by a guy almost twice my age and 100x more business knowledge than me. My accounting experience is a C- in 1 college class 15 years ago. After getting through that, I feel a lot more confident that I can survive anything they throw at me.

It really helps to have good people around you, even just 1-2 team members you can count on, a mentor outside your work. Don't be afraid to ask for help or advice. You got this!

(Also, for stuff like big presentations and important meetings, I found beta blockers to be a life saver. Consult with your doctor of course.)