YOU SAID:
what is your mom thinking of right now, I can guess: my watermelons are humongous
INTO JAPANESE
あなたのお母さんは今何を考えているのか、私は推測できます。
BACK INTO ENGLISH
I can guess what your mother is thinking now.
INTO JAPANESE
あなたのお母さんは今何を考えているのでしょうか。
BACK INTO ENGLISH
What is your mother thinking now?
INTO JAPANESE
あなたのお母さんは今何を考えていますか?
BACK INTO ENGLISH
What is your mother thinking now?
That didn't even make that much sense in English.