My DD2s tongue thrust reflex didn't go until nearer 7 months. I gave her finger food to chew on and just kept trying with a spoon every few days. I just used Greek yoghurt that I had in the fridge for my breakfast.
My little boy did this too, it's very frustrating! Just keep offering a mix of spoon and finger food and it will eventually just stop. Think mine's stopped around 7.5 months, must have just even developmental because one day he just stopped doing it and started eating. Good luck!