What is the best respirator?

I have a gerson respirator from harbor freight with p100 filters. Despite that, i find dust in my respirator, and occasionally dust in my nostrils & phlegm. I check to make sure i have a seal every time I put it on, and i constantly feel suction as I breathe, so i know its fitting. I think the dust is getting through the one way valve for exhaling.

So help me god if i get silicosis or mesothelioma because a respirator said it was rated for something that its really not... i dont even know what I'd do. Frankly i like my lungs, and am kind of panicking.