Could my thermostat be stuck if the coolant jug is bubbling but temp gauge reads cool

if it bubbles, odds are head gasket is blown. compression leaking into cooling system, then coming out overflow tank.

A way to check for head gasket leak is to let engine cool all the way down then remove radiator cap and start the engine. If you see bubble right away it is head gasket. If you only see bubbles when engine is warm could be head gasket or you need to bleed the air out of the cooling system.

If by bubbling you mean boiling, then yes could be the thermostat or air trapped in the cooling system. Since they hid the thermostat way underneath (like the rest of the way the engine compartment was designed), they actually put a bleeder valve on top of the block at the front of the engine to assist in bleeding the system. However, if it bubbles when cold - then agree with the others - blown head gasket.