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!
"Was that bread you were eating earlier actually your breakfast?"
「もしかして、さっき食べてたのが朝ごはん?」は英語で "Was that bread you were eating earlier actually your breakfast?"と表現できます。「Was that bread you were eating earlier」は「さっき食べてたパンは」、「actually your breakfast」は「実際にあなたの朝食ですか」という意味になります。