Potty training was a huge issue for me too. I had to carry him all the way from my apartment, to the lift, and then outside. But the last time I could carry my dog with one hand was when he was 4-5 months old, so I had to think of something.
The catalyst was when I realised I have to correct him everytime he peed inside, right then and there AS HE PEED. I would say NO! NO MORE! firmly as he finished peeing. After a couple weeks of 'correcting him in the act,' he's never had accidents no more. There's no use in correcting after you find a pool of pee, it has to be DURING.