My Macbook's chat.db is missing some text data

So I'm doing some text analysis of my friend's and my text conversation. Unfortunately, none of the answers in the communities forum solved my specific use case.

We've been chatting since April 15, 2020.

The Messages app shows all of our text conversations since that date, from both users, on both Macbook and iPhone.

Also, all new daily messages are being saved into chat.db correctly.

All data exists on my iPhone.

However, ~/Library/Messages/chat.db saved all messages from my friend since April 15, 2020, but it saved messages from me since May 4, 2020. In other words, messages from me between April 15, 2020 - May 4, 2020 are missing in chat.db

~/Library/Messages/Archive has the '2019-02-14' folder then there's a gap, then the next folder starts at '2020-05-04', which is when it says my messages started.

So there's folders missing from '2020-04-15' to '2020-05-03'.

So I have a couple questions:

• Where is Messages retrieving my text data? How is it displaying Messages coming from me between April 15, 2020 - May 4, 2020, if no archive folders from April 15, 2020 - May 4, 2020 nor chat.db data exists?
• How can I get my missing text data from April 15, 2020 - May 4, 2020?

Things I've already tried:

• Enable check box for Messages > Preferences > iMessage > Enable Messages in iCloud
• Messages > Preferences > iMessage > Enable Messages in iCloud > Sync Now
• iPhone > Messages > Send & Receive is correct
• iPhone > Messages > Text Message Forwarding is correct
• Toggle On: iPhone > iCloud > Messages

One hypothesis:

I toggled "Send read receipts", and it may be during that time. Could that have affected it?

This problem seems like a special use case. Thank you in advance for your help!