Help, fear of reoccurring PPD

I had Postpartum depression pretty bad after my first child, unfortunately i didn’t seek any help and struggled alone with it for about a year. I have worked through a lot of the things that were holding me back, I was raised by a narcissistic father and had his condemning voice in my head. (Ive been through therapy for that) i was also afraid my husband would blame or condemn me if I let him know what i was going through. I was afraid he would take my baby. I have since completely opened up with my husband and my sweet mother in law. I am 21 weeks pregnant now I feel very emotional lots of ups and downs and I am worried about reoccurrence.

What else can I do to prevent Recurrence what should I do if I do get PPD? I have mentioned it to my Ob-gyn they seemed to brush me off.