Hi @koa, Welcome to Connect. I also have had my fair share of struggling with nasal rinses. My right nostril used to be really plugged up and congested and I went through 3 or 4 months of using a Mayo Clinic proprietary nasal rinse which I think one of the ingredients was mometasone. It never was a problem shooting the water through the left nostril and out the right side but sometimes it would take me a couple of tries on the right side. I found the NeilMed Sinus Rinse bottle the easiest to use. Here's some information that you might find helpful:
"What if the fluid doesn't come out my other nostril when I rinse?
Yes, it is possible to get water stuck in your sinuses from a sinus rinse. This can happen if your sinuses are swollen or if your head is not tilted properly. If you feel like water is stuck, keep your head upright for a while and try blowing your nose. The water should work its way out."
--- How (and Why) to Use a Sinus Rinse: https://www.verywellhealth.com/sinus-rinse-770624.
I don't have any medical background or training but I think if the solution passes through from one side and you still do the other side, the sinus rinse will still do some good. Have you discussed your problem with your doctor or ENT?