I tried my cider this weekend for the first time since bottling and there is very little carbination. Only a few bubbles. I left this cider in primary for 1 month and secondary for about 2 months and its been bottled since about late Jan. It was about 4 gallons and I used 1/2 a cup of sugar. It's been in my basement the entire time at about 64 degrees. Did I just not use enough sugar and if so is there any thing I can do do fix it?