My first son didnt turn until 38.5 weeks and this one just turned at 37+6 and they were/are big my first 9 pounds and 2 feet long
I'm 36 weeks and my baby is breech as well. I'm going to the chiropractor to increase the chances of her turning. The doctor says treatment with her starting at 35 wks has a 100% success rate and it goes down the further along you get. I would try that just to see what happens. Google the webster technique.
My baby was head down then at 37 weeks flipped head up. I was not a happy camper. Thankfully at 38 week ultrasound she was head down again and she had dropped. So doctor isn't concerned of her turning again.