Ok, now I changed the $listWeeks line to $listMonths and it worked. thanks for putting me on the right track..
This is the code:
$DF = "d M Y | D";
However, with this solution I have to manually change the $listMonths value and increment it every month for the previous events to be shown correctly.
Is there another way that works from "today" backwards, rather than from 4 years ago to "today"?