How did you know when your grief had turned into PPD?

Tomorrow it will be four weeks from when my water broke early.

I basically haven’t left bed for a month and I am not functional at all. I’m trying really hard but each day keeps slipping by.

I have a history of PTSD/depression/anxiety that I had healed from before trying to get pregnant.

I have never tried SSRIs and was able to heal without them but now I’m just kind of lost and not sure if I’m still in grief stage or if I have ppd or something else.