If you're not confident on your regular expression abilities you would not be able to use them effectively, they're a part and parcel of Perl, you'd be turning around in circles and circles when the answer lies just on the outside of it.

Review the regular expression once again, consider the first time you studied them that it was only a getting-familiar-with time, now group them around, those that match words, those that match numbers, those that work on boundaries of words and numbers and the modifiers that extend the flexibility of these regular expressions. At the end of it look at the anchors and non-capturing groupings.

Classifying a problem to smaller chunks can make you tackle it better. So go it spickles and cheers :).