TriCare and pregnancy. Questions please help!!!

So I recently just found out I’m pregnant and I thought I had this whole TriCare stuff figured out. I live off post and I do not want to be seen on post because I’ve heard a lot of things and it just doesn’t sound good, and seems stressful I wanna say I have TriCare prime. My husband is stationed at JBLM soo their hospital is madigan. I called the appointment line to set up an appointment and they stated that I could go to the south sound madigan clinic that is off post and ask to take a walk in test. From there, can they give me a referral to an obgyn of my choice?

I’m soo confused because some people say you have to be seen only on post by your pcm which I have no idea who that is or haven’t been seen by. And then some say you can go to the off post clinic and get a referral to an obgyn you want.

I really don’t want to be seen on post, is there any way to avoid that?? Please help I’m stressing out over this.