Searching for better oven spring/open crumb

1. Image

   
   Howdy y’all! Been a long time lurker finally gonna make a post see I can’t find some help from the talent on here. My bread has been turning out pretty good but the crumb always seems a little less open that’s I’d like and the oven spring could be better. Below is a  recipe description and photos of my most recent bake .

475grams bread flour

48grams fresh milled rye

24grams fresh ground spelt

370grams water (80%)

95grams leaven

10grams salt

autolyse flour and water one and half hours 84 degree water room temp (70ish degrees)

add leaven mix via Robaud method 6 minutes (till shiny and smooth) then placed in proofer at 79 degrees for 20 minutes.

salt mixed in and kneaded again via robaud method another 6ish minutes followed by 45 min rest in proofer at 79 degrees.

aggressive stretch and fold (almost like a lamination very extensible dough) followed by thirty minute rest. At this point dough internal temp has been in the 75-77 range.

4 coil folds followed by another 30 minute rest  

removed loaf shaped benches rest for 20 minutes shaped and retarded loaf for about 7 and a half hours in fridge at about 39 degrees. 

Loafs baked on a cast iron pan with steaming pot of water as well as tray on rack above loaf to trap steam, for 20 minutes at 450F. (I think my results in the Dutch oven seem better) 

then about 25-30 minutes no steam at 435.

overall I think it’s some tasty bread but I just want that darn  spring and more open crumb!! I suspect my bulk fermentation was cut just a little too short. I also think my scoring needs some work but I’m not too sure that would make too much a difference? judging the end of the bulk fermentation and when to shape is proving to be very hard for me!