Trying to latch, then pump, but output has dropped massively

Hi mamas,

I’m trying to latch my LO (almost 7 weeks) every time before giving him a bottle. I combo-feed, and trying to exclusively either nurse or give him my milk. I am an undersupplier and seriously started pumping 7 days ago. However, 2 days ago, I have been trying to latch him, give him a chance to nurse and then pump. Sometimes he latches for 5-10 mins, other times he screams his head off and comes off my breast. So not every time does he latch and he definitely doesn’t empty my breast in 5 mins(I think!). I have seen a massive drop in my already very low output since I started doing that. I can barely get an ounce from both breasts combined.

Before the 2 days of this experiment, I would get 35ml-45ml from both breasts combined.

What am I doing wrong ?