Hmmm, seems you're trying to eliminate "sound" in the car by insulation.
Most road noise is the resonance of the vehicles metal panels. Aftermarket stuff bonds to the metal for a reason. It adds mass. This helps to keep the panel from resonating. They also have other qualities that help eliminate sound, mostly "coverting" the sound energy into a different form of energy (essentially, dampening).
By just laying foam (underlay) on the floor you've helped some, but by using the wrong mechanism.
It's doubtfull if bonding the material to the car will help much more either. You really have to add mass to the panels.
I'm not saying all your efforts are for naught, just that they aren't going to as be effective as the proper materials (as you've found out already).
But your car is probably well insulated for winter