use strict;

my $data = join("", <DATA>);
print "data:\n$data";
# loop for each heading
while ($data =~ /\s*(.*?):\s*\n((.|\n)*?\n)(?=(\s*\w+:|\Z))/gc) {
   print "heading: $1\n";
   my $text = $2;
   while ($text =~ /\s{9}(.*?)\n/gc) {
      print "line item: $1\n";
   }
   
}

exit;

__DATA__
     Paragraph1: 
         text
     Paragraph2: 
         text1
         text2
         text3
     Paragraph3:
         text