How long do you pump for every 2-3hrs?

I wanted to breastfeed so badly but LO just would freak out every time I put him to the Brest and just wouldn’t do it. Anyways he’s only 5 days old and I had a C section. Iv been doing each Brest every 2-3hrs for at least 20mins each and I’m only getting a total of 1-2oz each time which isn’t enough for him.

Idk if 20mins is too short of a time or too long or what. I’m a FTM and have no idea what im doing.