Bubbling in primary SHOULD slow or stop eventually...Bubbling stopping or slowing down doesn't mean fermentation has stopped it ONLY means bubbling has. An airlock is a VENT, a VALVE for EXCESS CO2. It's not a magic fermentation gauge. When the majority of sugars are eaten in the initial burst of fermentation, lots of co2 is released. As it slows down, bubbling ceases or stops altogether because there's not as much EXCESS Co2 being released.
But that doesn't mean fermentation is over, just that it's slowed down.
Fermentation is not always dynamic...just because you don't SEE anything happening doesn't mean that the yeast aren't happily chewing away at whatever fermentables are in there....the only way to know comes from gravity readings, and nothing else.
Activity, action, bubbles, even krausen can be affected by the envoironment just as much as it being caused by the yeast...so going by that is NOT reliable.
If you want to know what's going on with your beer, then take a gravity reading. The only way to truly know what is going on in your fermenter is with your hydrometer.
Like I said here in my blog, which I encourage you to read, Think evaluation before action
you sure as HELL wouldn't want a doctor to start cutting on you unless he used the proper diagnostic instuments like x-rays first, right? You wouldn't want him to just take a look in your eyes briefly and say "I'm cutting into your chest first thing in the morning." You would want them to use the right diagnostic tools
before the slice and dice, right? You'd cry malpractice, I would hope, if they didn't say they were sending you for an MRI and other things before going in....
Counting bubbles does not equate to anything usable in fermentation. It's not like "x bubbles/minute= y gravity points." It just means that co2 is being released....but it could also NOT be bubbling, and still fermenting away.
Relax, leave your beer alone and let it do it's thing for a couple more weeks, and most importantly, IGNORE what your airlock does or doesn't do.
In fact you might find this discussion
on the superfluousness of airlocks something that will help you get a handle on this. It was started by a newer brewing who just grasped this concept.