If the SG isn't lowering, it's still fine to bottle.
Airlocks bubble or don't bubble for many reasons. One, believe it or not, is barometic pressure changes! I've noticed the day before a big storm, my airlocks on bulk aging wine will bubble do to that. Weird, but it's just a pressure thing.
Temperature changes do it do, of course. Even warming up 1-2 degrees will cause an airlock to bubble.
Broken Leg Brewery
Giving beer a leg to stand on since 2006