It's probably bloating. Your uterus is still really small so it can't exactly be pushing your stomach or all that much. Bloating can really be crazy though.
^^i agree ur just bloated ur baby is still very very very tiny at 10 weeks n bloating can really feel like ur showing but u still have some time to go n don't rush it lbvs having a belly is so painful n uncomfortable specially at night lol
I had the same problem. Thats the reason i knew i was pregnant because my belly was big & hard. I thought i was gonna be pregnant with twins lol but its just one baby in me.