Has anyone had experience with delayed postpartum depression?

My daughter is almost 14 months and I've been feeling really down for a while now and having mood swings. One day I'll be fine and the next day I can't stop crying. I thought it may be just PMS because I've experienced that before but then I noticed it happening at all times of the month.

Depression runs in my family and my mom had PPD but I've never had an issue with it. I didn't think I could still get PPD this late until I read about delayed PPD.

Anyways I'm just wondering how did you know you had it and what helped you?