Check out
www.postpartum.net. There are volunteer counselors available who can help by talking with you for free. This was my lifeline when I had postpartum depression.
Also, I'm wondering have you looked at the events that preceeded your first situation with PPD? Have you been able to identify any areas of stress to be wary of? Had you recently moved? Did you have a difficult birth and/or recovery? Did you have breastfeeding difficulties? Did you baby suffer from colic?
Examine your attitudes toward your first birth that may have contributed. Depression is the result of unfulfilled expectations. Having a new baby is often much different than what we picture in our minds. For example, I thought I was doing my husband a favor by not asking him to help me with the baby at night. But as I was recovering from surgery, that and establishing any breastfeeding relationship can have bumps along the way, I just could not do it all. I was exhausted! I was trying to do everything for everyone. I know now looking back that I would need to great adjust expectations for myself if I am to have another baby.
I like the idea of hiring a mother's helper. I also think it's important to try to build up a support network before giving birth -- do you attend an API Support Group or another mothers' group? Don't be shy about asking for help!