A lot of things can be wrong, for example:
You mentioned carotid artery, we have it in both sides of our neck, so, that was a typo or you are only pressing on one side?
Another thing, position, you often see or hear about the "sweet spot", well, it's not the same sone everyone, you just have to try until you find it and apply the needed amount of pressure.
Something else could be your physical condition, being overweight could make it harder as you would need more pressure.
That's all i can say, maybe so wish to check the hanging megathread and the night night one, they talk about the sweet spot there and give some advice.