is my friend right that im just being extra?
Well, that's sort of the difference between normal anxiety ("everybody gets nervous") and an anxiety disorder. You know you should 'just take the class', because it's in your best interest to do so, but despite knowing that, you can't seem to force yourself to do it. You get diagnosed with SAD when your anxiety causes you to act in ways that are damaging to your well-being.
A normal person may be anxious about taking the class, but at the end of the day they want the credit more than they want to avoid taking the class. A SAD person may want the credit, but at the end of the day, they want to avoid the class more than they want the credit, even though not taking the class might have terrible drawbacks.
Therapists are there to provide additional support for a person with SAD so they can do things that other people can do without that support. (That's how it's supposed to work, anyway.)
Edit: Fun fact, I won an award for public speaking when I was younger. And I was a drama nerd in hs. I performed in front of the school a bunch of times. I was never really that nervous about it. But my anxiety didn't start until toward the end of hs. I'm not a lifer like most of the people here.
I don't really have any advice, because if forum advice worked, I'd have a job already instead of worrying about being homeless.