I believe I know my "problem" if my final end product after letting rise for the second time and everytime I get a denser dough like bread, is this because I am not final proofing long enough?

Using unbleached "All purpose flour"

Sponge is rising for approximately 90 minutes

Combining sponge to dough mixture.

Kneading dough for 15 mins by hand seems to pass the window pane test for elasticity.

Letting rise covered in plastic 4-5 hrs on top of stove

Pounching down Dividing dough for loaves

Proofing in (in home oven) covered with towel aprom 4-5 hrs

Baking @350 till internal temperature temp reads 195°