I'm sorry you're going through all of this, ledbetter!
Do you have any idea of what's led you to feel so down? Can you tie it to anything else -- lack of sleep, overwhelming responsibility, life events? Were you diagnosed with PPD, by chance? (I ask b/c you mention you're still nursing and PPD can flare up off/on for awhile.)
Do you think there's a possibility that this could be a PPD flare-up? My understanding is that it can really last for a number of years. Also, any changes in nursing can cause hormonal fluctuations which also don't help. :/
I was diagnosed with PPD two weeks after giving birth. My midwife suggested Lemon Balm tincture and I ended up taking that as well as Elm Flower essence. I still take them whenever I'm starting to feel overwhelmed or upset and it seems to help. It took probably a week or so after i started them the first time to notice a difference, but they definitely helped me.
Please make sure you take care of yourself! Get plenty of rest, eat as well as you and make sure you take time for you, too. Do you have any hobbies or activities you enjoy doing? (Or, at this point, can imagine enjoying?) Plan a date night with your husband and go out and enjoy each other's company.