| | Why are you still married?
You sound like a reasonably sane and healthy young woman, perhaps wanting kids, certainly wanting love and sex. Your husband doesn't seem capable of either. The sad truth about Bipolar is it doesn't get better, lithium can help the ill person cope with life, smooth out the mood swings, but until a miracle happens don't expect real changes.
I'll go another step forward and ask why are you still married?
Even the Catholic Church would grant you an annulment though it takes many years, a civil no fault divorce, perhaps with alimony would be granted in every state, many within a year, some less as fewer divorces are being filed due to the economy.
Your husband's desire to stay married wouldn't count if you filed, many states have simple, inexpensive ways that don't require lawyers. If your household assets are not large, you risk little with a do-it-yourself divorce. Yes, divorce is not fun, but it is better than the alternative.
I urge you to think how you want to live your life. Good luck.