The pressure varies depending on how big the pipes are, how far they are away from the pump, how dirty the filter is, whether or not there's a heater, even how many returns there are and how big are they. How often do you backwash. I can usually go nine months to a year between backwashes. If someone suggested you do it monthly, that may be why you see no change; it isn't dirty!
Ten psi seems a bit low, which is good, if it's accurate. Does the gauge look okay? Is it faded and hard to read? Does it go to zero when the pump is off? Gauges are usually only good for a few years. You might consider replacing it. It's not a difficult job.
Not knowing anything about the age of the filter and all is worrisome. I know, been there.
At some point you ought to put on the grubby clothes and open the thing up just to have a look at things. You'll be cleaning the grids annually anyway, the beginning of Summer is as good a time as any. Besides
this tutorial, there are tons of videos on youtube, probably some with your exact filter. Dirty clothes, some rags, some pool lube, and a hose and you're in business. And then, when you reassemble it and add the fresh DE, you'll know precisely what your clean filter pressure should be.
