Can anyone help me break down insurance?

So I went to a Rheum who said I was a “slam dunk” for EDS. He listened to me, got me pain meds, and a bunch of referrals. The only thing is he didn’t officially put down the Dx due to insurance reasons. I know EDS can affect insurance negatively, but can someone tell me how?

The thing is, I’m 24, almost 25. I’m on my moms federal insurance right now which is really good. I’m working at a bank that has decent insurance, which I’ll ideally be on when I turn 26. Would it be better to ask for an official dx before or after that insurance switches? If I do it before, will it raise my premiums? Will it get me better treatment?

Thanks to anyone who has insight!