The first text you send to Qeepsake is always attached to the most recent question Qeepsake sent you. Qeepsake doesn't interpret each journal entry to determine whether, based on context, it's a response to a question or a random text. So if you send multiple texts, in response to several questions you missed, it won't work properly. If you're trying to respond to a past question, your best bet is to edit your journal entry to include that question's wording.
The easiest way to check and edit your entries is by downloading Qeepsake's mobile app.