I guess that was your breakfast you were eating just now.
1) Was that your breakfast you were eating just now?
「さっき食べてたのが朝ごはん？」
「さっき」は just now と言えます。
2) I guess that was your breakfast you were eating just now.
「もしかしてさっき食べてたのが朝ごはんかな。」
I guess を使っても言えるかなと思います。
ご参考になれば幸いです！
日本 
