My take on this is as follows:
10 lbs innitial fresh start up pressure sounds right, filter until 22 lbs and backwash to get 15-16 lbs - also sounds right - sand has now settled into place and is compacted to provide better filtration - thus 15lbs compared to 10lbs.
turn on system this year, filter never drops below 20 lbs - my guess here is you need a new guage - that's all, everything else is working as it should IMO unless you did not drain the filter over the winter and your laterals broke.
If you're not getting sand returned into your pool, your laterals are likely ok, and your sand is likely of the proper type.
Install a new guage (only 10 bucks) and report back - this seems to be a normal part of the whole process that continually gets overlooked and is the thing that breaks most frequently. (esp. if left out over the winter - most remove the guage and store it indoors)