G'day Kiwi Man. Welcome to Apnea Board. (And if I may ask... what's a kiwi doing in Canada?)
Perhaps your doc was in a hurry, or maybe she was dumbing things down (because patients can't be expected to understand these things, right?) but what she told you sounds not entirely correct.
We have software to interrogate the machines and provide a breath-by-breath visualisation of exactly what happened all night. Surely the clinic has the Philips software (Encore Pro) to analyse the results for their patients? She should be able to tell at a glance how you're going.
Now she was correct in that large and persistent leaks can and do reduce the machine's ability to diagnose and treat apneas. Did your doc quantify the leak situation? More importantly, what did she offer to correct the leaks? It may be that your mask is unsuitable for you (every face is different) and that you need to try something else. I see you're using a nasal mask - perhaps the air is leaking through your mouth. Your bed partner would be aware if this is the case - it makes a very distinct sound. In any case, read up on masks on Fred's excellent mask primer:
http://www.apneaboard.com/wiki/index.php...ask_Primer
The oximeter will give you some further information but t's not really a diagnostic tool for apnea. Some people experience apnea with only minor desaturation while others have desats for reasons not related to apnea. It can't do any harm to have extra data, but it's scarcely the "gold standard".
Finally, I agree with all above who have suggested you download and use
OSCAR - it's a great piece of free software which will give you an enormous amount of detail about your breathing all night long.