I started a starter almost a week ago. Today is day 6. It started off promising. But then... I live near Rochester, NY and it got cold! The heat is not on in the house anymore so "room temperature" isn't really room temperature. The last 3 days were barely above 6o for highs, around 50 for lows. Could this be my problem?

I basically used the recipe for a starter from the Breadbaker's Apprentice book. Whole wheat flour, and pineapple juice to start. Then switched to unbleached AP flour for the daily feedings after that. Pineapple juice for the first 2 days, filtered water after that. I put a rubber band on the jar I'm using to mark where it starts. The starter IS bubbling and growing some. But less than an inch above the mark after 24 hours still. Definitely not doubling, even after 6 days. 

Should I just keep doing what I'm doing? Feeding it every 24 hours until it starts doubling? It is doing something and not completely dead. Should I leave it alone for another 24 hours to see if it will grow more? The temps are supposed to get back to the low to mid 70s for highs in the next couple of days. Is it really just because of the cold spell that started right after my started started to come alive that isn't letting it double yet?

Thanks for any help or input.