Having a really hard time breast feeding 😔

Diana • 20 y/o. Mommy to a beautiful baby boy named Jason, pregnant with baby #2 due Sep 2018.
Hi guys! My baby is only 3 days old and I'm having such a hard time breast feeding, he's latching on great and he loves to eat but it's just so painful for me. I literally just grit my teeth and breath during every feed. Same goes with pumping. It just hurts terribly, and to make things worse my milk still hasn't fully come in yet so I'm hardly able to get anything out 😕 I feel like I'm starving him at times. I've broken down crying twice already, and ive decided to start supplementing with formula just a little to give me peace of mind but I just really don't want to give up so soon. And I don't have anyone at all to talk to and relate to, please if there's anyone out here who took the time to read this and has struggled too, please give me some advice I really need it right now.