Overactive letdown

I'm pretty sure I have an overactive letdown. My baby boy coughs and sputters at the breast when I'm just beginning to feel my letdown. Poor little dude. And after he's gassy and visibly uncomfortable.

Anyway, anyone have any tips on how to deal with this? Will it always be this way? I've tried leaning back and nursing but he didn't nurse as well. I'd hate to pump before and then do nothing with the milk because I know you're not supposed to add to stored milk. Peas help. Lol