Reproductive endocrinologist

Halle :)
I'm going to be seeing an endocrinologist in the next week or so. A brief summary, my husband and I decided to ttc over the summer. I stopped bc in July and had my next period in August and then just never got another period. I made an appt with my regular doctor and had some blood work done last Friday. Got the call today that all my levels were normal so they sent a referral to an REI and now I'm waiting for them to call me to set up an appt. anyone been through this before? Any words of advice, questions I should ask? What should I expect with this first visit? Thanks in advance!