Give him a chewable that lasts a long time. Take him out at night a lot because they are more alert at night and use their ears to point towards strange sounds. Make him really use those ears. It's not too late.
I would bet, from what you described, the ear will come up on its own. Big frame, teeth are not all the way in, good history. Jupiter (my GSD) is Almost 9 months and had a left ear issue. Teeth started bleeding real bad around 7 months and the next 2 or 3 days later it went up. was a little floppy while running but they are catching up with him finally. Good Luck!
He does have back molars coming in also. I will keep taping and checking every 7 days.
i can't help other than a tip. people don't count in weeks past 8 unless they are a pregnant female. i have no clue what 29 weeks is. sure i can divide but who likes to? nobody.
hope the ear goes up. that's why it took over a year to find my last puppy. i needed a good breeder with pups with ears up and ready to sell at 8 weeks. even my pup before that, half the litter was ears up and half down. i picked the most ambitious/wandered off more with ears up. i could be wrong but it the are up at 8 weeks, they sometimes go down again and back up at teething but you know they'll go back up.