Oversupply and Overactive Letdown - How long?

Kinda long, but here's our story:
DS was born weighing 9lbs 3 oz.  When we were released from the hospital, he was 8lbs 6oz.  The LC at the hospital said he had a good latch (indeed, he latched on right after birth!).  He didn't nurse the greatest while we were in the hospital.  The day after we came home from the hospital, we went to the ped for a weight check.  He was down to 8lbs 5.2 oz, very close to 10% loss.  The newborn nurse watched him nursing and declared he was a lazy eater.  He would latch, but wouldn't get the strong sucks going.  She gave us several stimulation techniques to try (tickling his feet, breast compressions, stroking his spine and chin, raising his arm like a pump, etc.) and I was to nurse him every 2-3 hours.  The next day we went back and he gained 4 oz!  They wanted us to come back in another 2 days since his wet and poopy diapers weren't quite where they wanted them.  When we took him back for that check up, he had gained another 8 oz!  I no longer had to stimulate him to get him to eat right.  So he was only 2 oz away from birth weight at 6 days old.  They said everything was looking good and to come back at 2 weeks.  Since his weight gain was going good, we were given the green light to let him start sleeping longer at night.  Of course, that evening he started cluster feeding and cluster fed for the next few days.  It was hard, but at 10 days he settled back into an every 2 hr feeding schedule.  Then at 10 days old, he started spitting up.  At first I wasn't too concerned, but then it got to be that he was spitting up after several feedings a day and it seemed like almost all of what he ate was coming back up.  Our DD was sick with a fever, so our first thought was that he got her cold.  His poop had turned to a green color as well when they were previously mustard yellow and seedy.  We took him to the peds and he had no temp and they weren't concerned with his poop color.  He was 9lbs 5.5oz, so above birth weight.  Dr thought I had an oversupply/overactive letdown and advised to pump before feeding him to see how it went.  I contacted a LC as well, and she advised the same thing over the phone (I am to call tomorrow to let her know how everything went).  I am only feeding on one side per feeding.  I pumped this morning for 2 1/2 mins and got 1.5 oz out of the breast I was going to feed him on!  After feeding him, he only spit up a little.  The next time I pumped, I got 1 oz.  He didn't spit up after that feeding.  The next time, I did not pump, but fed him reclined against pillows.  He spit up, but not as much.  I was worried that this might be reflux, now I'm not so sure.  So my question is, how long does it take to regulate an OS/OALD?  Will it be several days/  How long should I pump?  I've read that some babies come to tolerate and handle it better, and as the weeks go on, your body regulates better as well.  I never had this problem with my daughter and happily nursed her for 13 months and I thought it was going to be much easier this time.  It's gotten very disheartening, to the point where I've considered throwing in the towel on breastfeeding this time around.  Sorry for the long post, but just looking for advice/reassurance.
Thanks