Postpartum depression

What is the treatment like and how long does it typically last? If it's a forever thing, how does TTC and meds work? My daughter is 5 months, so it's not just "baby blues."  I'm not sure if it's postpartum depression or more situational sadness/stress... I hate my job, I'm overweight and having a hard time losing, money is tight, and my mom just had a heart attack (she's okay, but still scary).  I want nothing more than to quit my job and be home with my girl, but it won't happen for a few years while we are paying off some debt. Please advise :( thanks. I'm just having such a hard time and don't know who I can talk to about it. I feel like everyone in my life is waiting for me to screw up somehow.