1988 Chevy Nova heater won't heat

My heater had not been heating at all until I did the following. Disconnected the hoses and hooked them in line avoiding the inside adjustment of heat because it was inoperative.

This did not help. Changed thermostat, this did not help. Changed the upper rad hose because it was collapsing shut, this helped and got heat up to luke warm where it is now at. I just cannot seem to get it to blow hot like it should and had.

Heater hosed are hot to the touch in and out. Hose hot going into the thermostat but freezing cold coming out and heading to the bottom of rad. Bottom radiator hose seems as though there is no water in it or pressure of any kind this is with the heater on full. Please help if you can with what I can do next