Verdict is in, it was the water pump. The impeller was spinning on the shaft so no wonder it was overheating because it wasn't putting out any flow.
Looks like the head gaskets are fine (thank God), the heat is back as the coolant is now flowing. Ran the car for 45 minutes and the temp never went above the "M" (just above half way, probably because I put the stupid winter thermostat back in lol).
So many thanks to everyone here who diagnosed it was the water pump. You've all proven 2 licensed mechanics wrong lol.