Backwash slow pumping?

Since I am opening up my pool, I backwash every hour to hour and a half. When I turn my pump off and turn my dial to "Backwash" it takes a good 30 seconds to a min before water starts pumping out of my waste line. Do I have a clog somewhere? Ive checked my line coming out of the pool, cleaned my skimmer basket and stuck my hand down in where the skimmer basket it at to make sure nothing was stuck. I am at a loss of why its taking so long for the backwash to start working. Also when it is pumping water into the skimmer basket (While on backwash) the water is pumping slow. Could I have a loose seal around my lid letting air in possibly? And the other thing is after I backwash and set my pump back to filter my PSI gage reads 2 to 5 psi's is that normal?