I just wanted to pop in to offer a little btdt advice. First off, try not to worry that your supply is diminishing. If you had OS, then its a GOOD thing that your supply is diminishing, and only being able to pump a little extra is what's normal. Pumping a bunch extra is what OS is, right?
As for OALD, I did notice, with my first, that once my supply evened out, the OALD wasn't as bad. But my OALD doesn't stop with the first letdown...it continues to gush until I am empty, which is uncomfortable for the LO. I just have a very fast flow, and require very little from the baby to keep it moving. It took some time though, and I can see that's happening now, as well.
Good job for sticking it out even with the problems!