How to help engorgement

So I’m trying to only breastfeed mainly, not pump because I hate pumping. I know I’ll have to when I go back to work at 6 weeks pp(I’m only three) and I keep getting engorged. My son eats enough I’m assuming, because he’s gaining weight and poops and pees a lot but he only eats for maybe 5-10 minutes on one side and that’s it. So I’ve had to pump to relieve engorgement but now I’m afraid I’m going to have to pump after every feeding now. I use to get 3oz combining both breast but today I got 6oz. Am I creating an over supply? And how do I help engorgement without making an oversupply?