My pump at low speed typically runs at 5psi.

Have you checked the obvious--is your sand filter completely full with 325# of sand? When my filter was installed, the bozos were putting in 150# of sand and I caught them and made them add the extra 50# because it is a 200# filter. Too little sand is not good. Are you sure they used filter sand and not sand-blast sand (which is cheaper)?

Also a lateral in the filter could have been damaged by the installer--if sand gets in the pool, that's a clear sign.

I almost think you should empty your filter and install 325# of filter sand yourself, see if that fixes it. Watch the sales: Filter sand can be had for $5 for 50#--$35 to replace your sand.

If the sand is OK, you can also use Pocono's DE trick to both better your filtering AND increase your pressure. It's cheap and those of us who use it think it works really well.

Also, as your filter sand ages, it should get dirtier and increase pressure--and filter better.

Just some ideas to check. I sure lots of folks have other ideas, too