worried about baby not getting enough milk.

Amber
I'm a FTM and I'm just so worried my LO is not getting enough to eat. I'm trying so hard to be confident that my breastfeedings are good enough but he's such a small baby. He is 4 days old he had 3 poopy and 3 wet diapers today. He had some uric acid crystal that freak me out because they look like blood in his urine. I hear they can be normal but should not persist past your milk coming in. My milk came in this morning but it's not engorged yet. He feeds every 3ish hours and feed from each breast for a little over 10 min. Does all this sound normal or do I need to supplement. I just don't want to hurt my little boy but I want so desperately to breast feed him.