I would have suggested a second opinion from another physician when Prozac was causing you to have manic episodes that they treated with medication for bipolar disorder.
My main concern is that Lithium has a very narrow therapeutic range and you should be having your levels tested regularly to prevent toxicity. As I said, the boundary between therapeutic levels and toxic levels is quite narrow, and you could be putting yourself in harm's way by going the "natural" route without proper monitoring.
People can be on antidepressants long-term, just like they can be on medication for Type 2 Diabetes long term. Depression is an imbalance in brain chemistry, which can be endemic (part of your usual brain chemistry) or related to other external factors, like stress, lack of coping skills, poor self esteem etc. It can be long term or temporary. Antidepressants have come a long way since Prozac - maybe you need to try a different medication than Prozac. Newer ones like Pristiq combine the SSRI (Serotonin Specific Reuptake Inhibitor) of Prozac with an NRI (Norepinepherine Reuptake Inhibitor) with good effect.
It's important to make physical activity and healthy lifestyle a part of your daily routine. Start with walking, increasing the duration and intensity of your sessions. Make better food choices, which along with exercise will contribute to your overall sense of accomplishment in self care.
Find something you think you might enjoy and join a group who enjoys the same activity. There are lots of choices - check for groups in your area.
Finally, be kind to yourself. Being part of a high control religious group like the JWs does a number on your self esteem, and if you are being shunned by people who you were once close to, that makes it all the worse.