I tried to use a neti pot/nasal irrigator, and I just immediately started suffocating. Am I just doing it wrong?

I got this nasal irrigator, and I followed the instructions completely. I only used distilled water and I used the saline packets. The instructions say to keep head straight, but guides online said to try tilting your head to the side. I tried both.

But, as soon as the water starts flowing, I feel like I'm drowning. I keep my mouth open and *try* to breathe through my mouth, but it's just completely blocked. I did my best, and my nose does feel slightly better, but it's just extremely unpleasant. Is this normal, or am I doing it wrong?