Feet get cold from sinking cold from the cold ground into your feet, not by the cold air. The warmest cold weather boots have more insulation under the foot than what surrounds the foot.
A couple tips:
Buy cheap closed cell foam pad and stand / place your feet on, sit on, lay on when you stop and not moving.
When sitting or not moving, sit so your legs are not restricting the blood flow down to them.
When lacing your boots, stand full body weight on one foot at a time. This will allow full body weight on the foot to help not over tighten the laces.
When lacing boots, do not run the laces over the top of the foot but run the lace up the holes. At the ankle, lace as normal. This will help keep the laces from cutting off circulation on top of the foot yet allow the lace to snug up the ankle for support. Unlace your boots when stopping and sitting for long periods. There are more lacing tricks.
Run Degree antiperspirant all over your feet before heading out; between toes the whole foot. Just like underarms, this will keep the pores of your feet closed and not sweat as much meaning drier warmer feet. Plus, feet and boots will not get damp from the sweating and not stink or need to be aired out and dried as much. I carry a travel size Degree with me on all my trips.
Never use 100% wool socks. Use a 60/40 combo so the sock has the best performance of wool and synthetic materials.
Good luck
I have a problem keeping my feet warm on cool/cold hunts as well. One thing I have found is that it does not matter how well the boots are rated if you cannot keep your feet dry. I have had boots rated for -35 on hunts in moderately cool weather (teens and 20's) and without a good wicking material and an absorption layer it did not work. Just a reminder to remember the basics.
If that does not work buy some heat packs!
Best of Luck!