Allergies and irritation after Neilmed sinus rinse?

I got it a week ago and used it every other day. So far I've always gotten more stuffy after use. Especially yesterday, where using the bottle made my nose more irritated and blocked all night. It doesn't help much the day after either.

I lightly squeeze the bottle and lightly blow my nose after each rinse as it says. However I get irritated after, leading me to blowing harder and sneezing.

What am I doing wrong? Do I have to keep using it more and use it daily before I can prevent allergies?