fantastic, eulalia! one vial hurdle overcome.
I'd second the advice about leaving potties in your ds's sight and within his easy reach throughout the house. Our ds, potty trained for some months, still prefers the potty to the loo. He will`drag it to a nice, warm interesting place of his choosing, ie three feet in front of the TV, surrounded by assorted company - rather than sit on the cold and lonely loo by himself. And we have a warm house, carpeted throughout, (even the loo - the previous owners loved carpets)with the central heating on most of the time.
It also helped enormously to let ds run around minus pants when he was getting used to the potty.To be honest he still does this six months on. Not a good time of year to strip off, but if you could make your house extra warm for a few days it could speed things along. If not possible, as someone else said, keep your ds in easy pull down track suit bottoms.
I still soemtimes pop a nappy on if my ds has a daytime nap longer than an hour, but since his sleep pattern makes this a no no, long naps are a rarily. I used nappies for journeys, as and when it suited, for both of my sons when I was potty training them. It didn't confuse them or halt potty training progress at home. In fact quite the opposite - the sometime reminder of being put in a nappy like a baby soon became a turn off for them and reinforced the message that potties were good news.
Best tip I can give you: Be shameless in asking for help from nursey/playgroup workers, as long as they are willing. I'd say 70% of the potty training for my first son and 40% for my second was accomplished by nursery workers. My sons were far less blase about having accidents when taken-for-granted mummy was not around.
Hope there's light at the end of the tunnel for you soon!