Full Term Low Birth Weight ?

Ariel • Married to the love of my life for 8 years❤️ Have a Baby Boy 12/28/15 💙 & expecting 9/7/18 💛
Anyone have any really small babies? I had a scheduled c section last Monday (12/28) due to him being breech. I was 39 weeks 4 days. I measured right on track my entire pregnancy. His sonograms always were normal. 
I remember no one ever giving me a guess as to how big he was because "they're never accurate" so I really wanted to find out how big he was. I didn't see him for about 5-10 after he was out so I was pretty anxious. When they called it out I was confused. 5lbs 7oz ! My husband & I were in disbelief. I didn't drink. I don't smoke. I Ate.. Why is he just so tiny? I guess I feel guilty. I know it's not my fault but I feel like it is since he's term. Anyone else? I find preemie posts... But he's not a preemie. He's just preemie size. & of coarse they hardly make things small enough to fit... So his clothes are just gigantic as of now.