Nursing Difficulties

I spent a week trying to build up my milk stash in the fridge, so I could sleep for longer stretches at night, and Bryan could bottle feed Josiah. It seems that all the pumping after Josiah ate significantly increased my milk supply, which I thought would be a good thing. It seems to have had a bad effect on Josiah though. If I am out all day with him, and don't both feed him and pump, I get so full of milk that it nearly drowns him when he nurses. He sputters, chokes, frequently pulls away, and somehow gets too much in him almost every time, and has massive quantities of spit up afterword, from both his nose and mouth. The big spit ups must hurt or scare him, because he usually cries inconsolably for 10 minutes after. It's really hard to see. He has none of these symptoms if he drinks from a bottle, or if I have recently pumped. This has been going on since the middle of last week. A new problem arose yesterday; now that I have weaned the nipple shield on the right side completely, and have this excess milk that comes so fast, Josiah doesn't nurse well with the nipple shield on the left side. He either falls asleep with the increased effort and little return; or he gets frustrated and pulls away, or shakes his head, or bites harder, or worst of all pulls back and cries and won't nurse at all with it. This resulted in me trying to wean that side too, but it is not going well. It hurts badly. The latch is hard to get deep enough, and by the time Josiah finally gets it, he gets blasted with so much milk that he pulls away and we have to start over. I never thought breast feeding was so complicated. It is worth the health benefits and the money savings for me to try to work through the frustrations.
I spent today trying to improve things. I tried reclining after we get a good latch to slow the flow. It seems to stop the sputtering and choking. He still pulls away a lot. I try to burp Josiah several times during nursing. It seems to give me time to observe and stop him before he gets over full. He only had one really huge spit up followed by crying fit today, and I must admit, I was distracted and let him nurse too long. I only pumped when I got up and before the last feeding before I go to bed. I got 5.5 ounces out on the latter, and I didn't pump until it was dry. I tried to just pump until the pressure of the flow was more a drip than a spray. That's a lot of extra milk for one day. I also tried to keep offering the same side until it emptied, so that Josiah would still get some of the fat that comes at the end of a nursing session. It seems to be helping some. Josiah actually ate well once with the nipple guard some, and I was able to help him get a good latch without it at least 3 times today.
I hope decreasing my milk supply can happen as fast as increasing it did.