Why does it hurt so bad to pump? 37 weeks pregnant

I’m 37 weeks pregnant and I was curious how it would feel when I started to pump. I got a haakaa pump since it’s cheaper and it looked easy to collect milk with if I’m breast feeding and needed a little extra for later after my baby is here.

However goddamn it hurt when my breast got sucked into the flange(?) I was not expecting that. My breasts are sensitive regardless and it felt like they were being squeezed in such an unnatural way. I’m worried, I wanted to breast feed this time around, I never attempted with my daughter, but now after having felt the pain I’m unsure of how much pain I can endure? Plus I’d also like my bf to help with feeds so I’d like to pump occasionally. Also it would be nice to have extra on the side in case we go somewhere.

Ik most people say it hurts initially to breast feed but experiencing the pain first hand is another reality entirely. Perhaps I shouldn’t be pumping so early but luckily I did so I could know what’s in store for me while not having to go through it for a first time in the hospital bleeding and in other types of pain.

Any advice on how to bypass the pain when pumping and/or breast feeding? I didn’t end up getting anything from my lame attempt at breast feeding so my milk still hasn’t come in I assume.