你內心可能有懷疑, 為什麼我 選擇你的公司都唔選擇 A 公司呢 ?

Actually you shouldn't use "could", because it implies ability, but the sentence you want to express does not consist of such meaning.

Therefore, i would suggest you to write is as-
Are you suspicious of why I am choosing your company, but not company A?

Hope it helps~~~