It’s very hard to feel alone, I know. But it’s understandable why your sisters aren’t able to be more supportive. To them, your illness may be very frightening. From their point of view, if you have it, they might someday have it too. They would much rather think that you are being stubborn than ill. As for your husband, I think it’s probably much the same for him. To read about bipolar illness and understand it fully is to let it in that you really do have an illness that you will probably need to manage life long. “Getting it” is too threatening to the people who love you. That doesn’t mean that they don’t care. It doesn’t mean that they aren’t trying their best to be supportive. It does mean that their inability to get any closer to it leaves you feeling less supported than you would like to be. It won’t help to argue with people who are afraid. Instead, stick with your treatment, let them in on when you feel you are making progress and when you need some extra support. Share very specifically with them what you would find most helpful when you are down. When you ask for support , it may seem too vague and too big. If instead you ask for a five minute phone call once a day or for someone to cook a meal now and then, they may find it easier to respond.
Do a search on the Internet and find an online support group for yourself. When I looked, I found a number of reputable sites. You could also contact your local mental health center or hospital to see if there are any support groups operating in your community. Either way, talking with other people who are going through much the same thing is often very helpful and validating. If you have some compassionate understanding from others, the current inability of relatives to truly understand will be less painful.
I wish you well.