problem with fermentation process

i seem to be having a problem with my fermentation process. I bought one gallon of organic apple cider and one gallon of organic apple juice. i put a crushed up campden tablet in each one and let sit for 24 hours. after the 24 hours i added one cup of corn sugar and one cup of brown sugar to each jug. I put the yeast in warm water for 15 minutes before pitching as per the instructions. i also added 1 tbsp of yeast nutrient and energizer to each batch. the first 2 days i was getting one bubble every 20 seconds in each jug. after the 3rd day the bubbles completely stopped in the airlock. also there are very few bubbles floating on the top of the jugs so it doesn't look like a lot of fermenting is going on. its been one week and it seems ive had very few results. Am i doing something wrong? I do not have a hydrometer so i can not do any testing. I also started a gallon of mead at the same time at its doing very well. Any feedback would be greatly appreciated

Get a hydrometer. Baring that, give the cider a taste. If it's still sweet you may have a stuck fermentation or you may have a leak around the bung. If it's dry it's done fermenting.

What is the room temperature? What yeast and how much did you use? I have had extremely fast fermentations when my room temp is around 24 deg celsius, like a couple of days. In between, the airlock would go crazy for about a day solid then back right off and level out, leaving a fat yeast cake on the bottom.

Room temp and yeast would make a huge difference. As Fossey said.
get a hydrometer if you can, test some of the juice and find the gravity readings of it. This will tell you if your fermentation has finished quick.
For meads, ive used 1118 and it has finished fermenting within 4-5 days. and another took a week. Just depends if it wants to.

I forgot to add that in the post. I'm using red star champagne yeast and I store it under the kitchen sink with an average temperature of around 65 farienheit

I tasted the apple juice today and it tastes like dry wine. It's also starting to clear up. The hard cider still smells like sulphur but not as bad. Are they done fermenting?

Probably.