Cartridge filter pressure problems

Hi all thanks for adding me. I have been a pool owner for many years but have always had a vinyl liner pool and sand filter and always did my own pool work. I just moved to Fl. and now have a concrete pool with cartridge filter and am totally lost. My cartridge is only about 2 months old and despite all my chemistry being in normal range my pressure runs high between 30-35 psi. The water barely circulates at that pressure. I have been taking it out and cleaning it and it drops back down to 10-15 psi but only stays there 1-2 days at best. I have a filter bag on my skimmer to catch the leaves and small particles and my filter looks relatively clean when I take it out. Once I spray it down good as I said it drops to normal for a day or two. I keep my chlorine and PH levels within normal range and have not had any algae issues. My neighbor has a similar size pool and the same pump and filter and claims he only has to clean his filter about once a month. I miss my sand filter and being able to backwash. Any suggestions would be greatly appreciated