The aggregator’s Source Module field should be set to your Trigger module then.
That way you can combine all the bundles from the three emails.
This is covered in the Make Academy.
Hope this helps! Let me know if there are any further questions or issues.
— @samliew
P.S.: Did you know, the concepts of about 70% of questions asked on this forum are already covered in the Make Academy. Investing some effort into it will save you lots of time and frustration using Make later!