I'm having a hard time with knowing what to say. When I hear of low fluid, my mind goes to the worst thing, because that's what happened to my brother and his wife. On the other hand, what happened is extremely rare, so if it weren't for what happened, I wouldn't even be writing. But I don't want to scare you unnecessarily. I'll share, briefly, what happened with my nephew, but please, please don't assume that's what will happened. The odds are so much against it. The only reason I'm sharing is because I don't agree with the idea of pretending bad things don't happen and trying not to accept it. You'll see why by the end of the post. But, again, please don't assume this is what's going on. This is for general knowledge.
As long as they can find functioning kidneys and a bladder, I wouldn't worry overmuch. Do what the doctors say to stay healthy. If they don't find functioning kidneys, which is what happened with my nephew, or if it turns out sad for another reason, you will need to have a support system in place. Actually, I think EVERY parent needs a support system in place.
In my brother's case, they found on ultrasound that their son did not have kidneys at all. It was confirmed through several more experts. There was very little amniotic fluid because the baby couldn't urinate. Unfortunately, they let his wife's church people convince them that if they prayed hard enough, God would put working kidneys into the baby's body. Of course, that is not how it works, but they didn't accept that this was happening until the night before the birth. Now they have a little angel to watch out for their second baby, a healthy little guy. He will be one this summer. So out of tragedy, some good has happened. I doubt Christian would be here if Willis hadn't passed, not that we'd want such a thing to happen.
I'll keep you in my thoughts for a healthy set of twins. Please let everyone (especially me) know what you find out. I hope the baby is well, and I will sigh in relief. If something happens, please remember that there are people here and through your local groups that are here for you, as well.
Best of luck for two happy, healthy babies!