If there's no mold then it's most likely drinkable. I'm not certain I've ever had a mother stay submerged for that long, but it seems to happen sometimes.
Taste it once in awhile? Spit it out if it's rank? If the new scoby isn't spreading over the surface you might want to add some GT kombucha or apple cider vinegar. Or reassess your sugar and temperature content? Strength of the culture, temperature, and sugar content all could have a role in slow growth.