my black cloud has returned! Graves or PND?

Hi, welcome to the ehealth forum and I am glad to help you.
You seem concerned by the Postpartum depression (PPD) and Grave’s disease. You also made a mention of chronic depression in the past.
Graves' disease can lead to severe emotional disorders and can affect your mood causing either anxiety or depression. Generally, the more severe the thyroid disease, the more severe the mood changes.
In your case, depression symptoms might be due to PPD. PPD may or may not go away without treatment.Treatment for PPD can reduce the length of suffering and its severity. Various treatment options include:
•Medical evaluation to rule out physiological problems
•Cognitive behavioral therapy (a form of psychotherapy)
•Possible drug medication
•Support groups
•Home visits/Home visitors
•Healthy diet
•Consistent/healthy sleep patterns
You must consult your personal physician to develop a treatment plan that is right for you. This plan may include any combination of the above options, and might include some discussion or feedback from your partner.
So you must consult your personal physician for the proper diagnosis and its treatment as the same cannot be made online.
Hope this helps. Take care.
Note: This post is not to emphasise final diagnosis as the same cannot be made online and is aimed just to provide medical information and no treatment suggested above be taken without face to face consultation with health care professional.