Have read that taking sp helps make the pm work better is this correct. As writing and knowing does take time for the pm to work. I have been on pm for a month now taking 4 tablets a day.

Should I increase my does or add sp?

You'll hear and read all sorts of opinions on everything. Best thing to do is try it and see how it goes. I've used SP along with PM since my beginning 1.5 years ago. Who knows for sure what's going on but I've been getting results. I think there's some merit to the argument that all you need is PM. If I were to go back in time and start over, I think I'd use PM for 6 months or more and see what happens, then add something if needed rather than concocting a big cocktail right out of the shoot. It's up to you but please report back what you do and discover for the benefit of all.