Man... I can safely say that my pug goes to the door... almost every single time (unless he has an accident which happens from time to time... about 1-2 times a week). Strangely, he hasn't peed inside in over a month. Only pooped.
Seriously... they don't "tell" you guys??? As soon as mine goes to the door and sits there for a second looking at it... I let him out and he does his business. He's even barked & scratched at it numerous times when he's seen that I'm not paying attention to him.
I can sympathize with you :)
I have never had a dog that took so long to potty train as Poncho. He is now 2 years old and (knock on wood) he is finally trained.
It really does take a LONG time for them to be reliable and any change in their routine such as a vacation or biz trip can completely set them off track. Then you have to start all over again - super frustrating!
I too am using the bell method and I find it works very well (eventually). For example, when its raining outside and he's being stubborn and wont do his business at bedtime - he'll wake up at like 3:30 am and go ring the bell!! I am so proud of him actually ringing the bell that I jump up and take him out to do his biz. Keep in mind I live in an apartment 15 floors up and its cold - so its not a fun thing to do lol. But I am so grateful that he actually lets me know now.
The only time he has an accident these days is when the dog walker is late to come and take him in the afternoon while i'm at work. He can't hold his poop for more than 7 hours - understandibly!
So, I know its very frustrating but it will get better and eventually your puggie will be trained - hang in there!