Hi OP
I've been where you are, I've had those same worries, I promise this isn't forever! Those who are saying you 'just' need to do x, y, z havent experienced this problem so think it's easy - I was probably just as ignorant until I had DS2 and discovered they are all different. My eldest was so easy to train, I simply did the bare bum thing and told him to sit every 30 mins or so (tried from 20 months but he wasnt ready, potty as a permanent feature in the room from 18 months and we just tried every couple of months until one day he was ready) . He was a biddable child, once he'd figured out how to wee on demand he was dry within days, at 2 and a half. One of his friends was dry day and night at 18 months, her older brother wasnt ready until nearly 4 years old.
Middle boy was far more resistant, refused to use the potty and no amount of praise, rewards, stickers charts, frequent sitting, books, wet pants etc worked. Eventually he decided to wee on demand at 3 and a bit, but only in the toilet never a potty (poos were another story, would withold until nighttime nappy was on then go, this continued until he turned 4) - he never had accidents whereas big brother had needed frequent reminders and would often have wee accidents until he was 4 as life was just too excitingto stop for a wee.
Littlest I was so worried about, far too busy to sit on a potty or toilet, actually impossible to get to sit for more than 5 mins at a table or in front of telly nevermind on a potty or loo, had potty out from around 18 months but always refused to sit. Tried when he turned 3, did a week of no nappies, a hideous nightmare with no improvement, went back to nappies.
Tried again 2 months later, having found he loved Sonic the Hedgehog (discovered through a nursery friend). This time he would agree to sit for 10 mins if given a tablet with Sonic on - eventually we caught wees and gave lots and lots of praise. He was reliably dry 7 days later.
Poos however are still an issue a year on, and we've only just got rid of the potty as he absolutely refused to go in the toilet and would scream blue murder and withhold for days on end.
11 months is a long way off, you do have plenty of time. Look for something he likes (programe he likes, toy he really wants, computer game, book, chocolate whatever) and only offer when he is sat (I would skip potty and go straight to toilet with a little seat but onvs your LO will guide this). I know you've tried this before but if you give it a break for a bit you may find he developes an interest that you can use, then perhaps try again between Christmas and New Year, if not ready then February, if not then try Easter. Just because you've tried something before doesn't mean it's not worth trying again in a few months time. This is a tough nut for some kids to crack, you will get there.
My youngest (just turned 4) has accidents at school once or twice a week, his brothers never once needed a change of clothes at school. Reception teachers are used to this, they are very understanding and it's not an issue.
Good luck OP.