How do I pretty print time duration in perl?

The only thing I could come up with so far is

my $interval = 1351521657387 - 1351515910623; # milliseconds
my $duration = DateTime::Duration->new(
    seconds => POSIX::floor($interval/1000) ,
    nanoseconds  => 1000000 * ($interval % 1000),
);
my $df = DateTime::Format::Duration->new(
    pattern => '%Y years, %m months, %e days, ' .
               '%H hours, %M minutes, %S seconds, %N nanoseconds',
    normalize => 1,
);
print $df->format_duration($duration);

which results in

0 years, 00 months, 0 days, 01 hours, 35 minutes, 46 seconds, 764000000 nanoseconds

This is no good for me for the following reasons:

1. I don't want to see "0 years" (space waste) &c and I don't want to remove "%Y years" from the pattern (what if I do need years next time?)
2. I know in advance that my precision is only milliseconds, I don't want to see the 6 zeros in the nanoseconds part.
3. I care about prettiness/compactness/human readability much more than about precision/machine readability. I.e., I want to see something like "1.2 years" or "3.22 months" or "7.88 days" or "5.7 hours" or "75.5 minutes" (or "1.26 hours, whatever looks better to you) or "24.7 seconds" or "133.7 milliseconds" &c (similar to how R prints difftime)