Hand expressing

I posted a few days ago about having supply issues and my breasts seeming like they are not draining all the way. I found a video online about hand expressing and I have been doing that. Hand express for 10 or so minutes and then pumping after with the electric pump. I am getting more milk and it looks much thicker. I just wonder if I’m doing the hand expressing wrong because my breasts are really sore from doing it. Or is my body just getting used to ramping up production again? Idk they’re noticeably sore and they’ve never been before. Does anyone who frequently hand expresses have suggestions for this? I will post the link to the video that I followed.