i had blocked ducts recurring a couple of times after the first six weeks. i reaised it was from my own laziness in pumping out on a few unusual nites that my boy slept thru. baby also cried the first two or three times i latched him on to help me clear my blockages cos my breast was super hard and thus it was very difficult for him to get a good mouthful of my auerola with a good suction. but i tolerated the pain and his exasperated crying, and just kept telling him in a soft voice to please help mummy to help himself. thankfully he didn't totally lose patience and i think it was the fourth or fifth session after the blockage happened that i suddenly felt a softening and relaxation in my breast and heard the healthy suckle from my contented baby. do be patient and keep trying. i tried pumping, massage, hot compress to widen the ducts etc, but nothing worked as well as my baby's suckling.
as for whether you should still pump after nursing, yes you should esp if you feel full and you dont't want your milk supply to drop. i wake up in the middle of the nite to pump even though my boy sleeps thru nowadays. if you feel you dont't need so much EBM, my suggestion for you is to offer the EBM to your baby for the two FM feeds at nite as well. why feed your boy FM when you have more EBM to spare?
as for your baby taking only 5 min to suckle one side nowadays, this is normal as baby gets older and more efficient at nursing. you can try to offer him the other side after he has finished one. if he pushes away after suckling for a few moments, then just take his cue and let him be. pump out the rest and store. trust your baby to tell you when he's not yet full. =)