Easy One to See
Have a family member stand inside the house. Grab the house and spray the windows. Focus on the corners as that is the place where, if they are going to leak would be from there. If water can get through. So can cold.
Also, if your windows are single pane that could be an issue as well. Easy test there as well. Take some tissue paper or something else very light and flowie if possible. Tape it to the bottom window sill. Cold air drops as we know. This will cause the material, ribbon etc to move, showing you the amount of cold air come off the glass and down the wall to the floor.