Thermostat mod

Just been out and checked coolant level, coolant is sat right in the middle of the min/ max marks on the expansion tank, but squeezing the top hose it feels empty of coolant, and I'm not seeing coolant being fed into the expansion tank whilst squeezing the hose either. It's not used any coolant and when upto temp the top hose does fill with coolant from what I can tell, as it gets hot and rad gets hot, so I topped up the coolant higher, whilst squeezing the hose and got a flow of water back into expansion tank. Started the car and got a few very small air bubbles, before the car started warming and coolant started to expand, I tried bleeding the system via the bleed screw and got a constant stream of coolant, so beginning to think I may have or had an airlock