I think analyzing my play and finding my most critical leaks is vital in playing profitably. But even with the tracking software, how do I identify a leak and more importantly a critical leak? And how to proceed analyzing those hands to make better decisions in the future?

This is a good question. This comes down to filters, filters and more filters. Check your overall stats to see if there's anything out of line. Check your win/loss by position to see if you're doing what is expected (which is generally losing out of the blinds and winning everywhere else). Filter by certain hands or groups of hands (do you lose too much when chasing flushes/straights?). Filter when facing certain actions. Look to hands where you had big wins/losses and see if there was anything you could have done to increase the win further (i.e. you missed value) or limit the loss (i.e. was getting stacked a cooler or otherwise unavoidable, or did villain tip you off that you were way behind his range).

Thank you, I'll do just that!

A leak is best spotted when you say 'Oh' when something happens or you look at a stat.

Oh, They were stronger than I thought
Oh, How do they end up there with that holding
Oh, That makes sense now

You also need to consider any time your stuck in a spot and don't/didn't know what to do. Like getting caught in the middle/OOP too much and you feel like you're being taken off your marginal holdings too much. Sometimes these spots are meaningless one-offs, but when they become a pattern they need to be addressed, especially if you play in a Reg filled environment. GL

There should be a stats thread at the top here, you can check that, it has tons of useful info about tracking leaks.
You can also post your own stats to get some help.

Hiring a coach or someone who can analyse your database is probably the most efficient way to find your leaks.