I hear you with the breathing issue – I had the same problem for a very long time, and not attending to it led to habits that were hard to break when it finally came time to fix my breathing issues. I ended up having to abandon the tunes I had learned with breathing only at phrase breaks, and just go learn new tunes where I had the breathing right from the beginning. (I’m finally going back now to repair the old tunes).
First and most important – go buy some recordings of good Irish whistle players, and listen to them obsessively. Use them as background music whenever the people around you will tolerate it. Also take some time quietly alone, and really listen hard to what they’re doing with their breathing. I’m a very analytical person, so I found that it helped me to search up sheet music for tunes, and follow along with the recording, circling the notes that got dropped for breaths. But what you need, first of all, is to develop a clear imprint in your mental ear of how Irish flute/whistle music shapes its phrasing around the breathing pauses, turning a necessity into an expressive opportunity.
Now I’m no expert Irish whistle player, but I am an analytical personality who has been immersing myself in this very question over the last year of my playing history, and the following are some things I’ve personally observed. I’d be really grateful if more experienced players would correct me where I am misled, as I try to share what I have learned.
First of all, it’s not that the ends of phrases are bad places to pause for a breath (real players do it all the time!) – it’s just that it makes the music sound very predictable to breathe only there. In contrast, there’s a sense of flow that comes from running the music from one phrase into the next, which is why so many tunes have variations at the end of each part, so that the end of one section has the possibility of flowing smoothly into the next (if you don’t pause for a breath there, that is).
The most common way to preserve that sense of flow is to not take a breath in that predictable place, but to play through the end of the phrase, on through the optional pick up notes that lead into the next phrase, and then hit downbeat of the first measure of that next phrase – and then quickly snatch a breath, dropping an off-beat note. I can’t quite figure out why it’s so, but making first beat of the next tune-phrase into the final note of your breath-phrase somehow gives extra pop to that first/last note, which punctuates the sense of gathering momentum that you preserved by playing through the phrase break. The strength of that first/last note seems to serve as a momentum-preserving jumping off-poing for a little leap ahead in the tune, during which you steal the chance for a breath.
Of course, in some places the note folliowing that first/last note isn’t expendable, and you’ll instead want to drop the off-beat note following one of the subsequent strong beats. I have found that for me, it’s a matter of experimenting around, playing with different breath/phrasing options, and listening for ones that make musical sense to me. More experienced players I’ve talked to say that they can hear these phrasing options in their heads and their fingers and breath just do what they need to in order to make it sound right, but that was not the case for me when I started out. At first I had to play the options out loud so I could evaluate them, and then laboriously teach them to my ballistic guidance system – but I am noticing that now, with more experience, I find myself doing it occasionally with no conscious intervention.
In concrete terms, this means that you’re generally going to be dropping note 2 of a 3-note grouping in jigs, and dropping note 2 or 4 of a 4-note grouping in reels and hornpipes. But the key is figuring out how to make your breath-phrases speak musically, almost weaving a commentary around the predictable phrasing possibilities that come built-in to the tune.