Potential for PPD/ How to tell my Doctor?

So i’m currently almost 8 months pregnant and my depression, especially recently has spiraled out of control, i don’t have suicidal thoughts but i feel so extremely alone and defeated, always feeling so worthless and i can never control my emotions I definitely don’t want to die either but sometimes i just wish i could disappear with how stressed i am. I’m worried about postpartum depression with how severe my depression has got lately. I’m only 19 and i don’t know how to tell my doctor exactly. It’s not that i’m embarrassed it’s more that i’m just scared and i don’t even know what to say. Ive always had trouble saying to anyone that i’m feeling sad. i’ve always kept my emotions built up inside because i didn’t want people to know. What is a good way to go about bringing it up in a conversation that gives me the least amount of anxiety possible? being at the doctors already makes me anxious and i’m scared if i try to talk to her about my depression, with how things have been lately i won’t know what to say or i’ll break down. I also worry about my stress levels when i have “episodes” of sadness and uncontrollable sobbing how it affects my baby. I always feel so guilty for crying and potentially hurting or stressing her out it makes me cry even more.