It's called oligohydramnios if your fluid measures less than 5 centimeters. From my understanding lowish fluids are fairly common in the last few weeks of pregnancy, and may not be too big of a deal. These are fluid levels below 10 but above 5. True oligohydramnios is extremely serious, however, as it can indicate that your baby has a kidney problem or that your placenta is failing. A woman with oligohydramnios should not have a homebirth, and should be under the care of a perinatalogist.
If you have slightly low fluids, I suggest long baths everyday and drinking a ton of water. Also rest as much as possible.