I don't know if this will help or not (and for the record, I tend to breathe in and out my mouth, too) but for the longest time, I used to count four breaths in and about 4 out while I was running. I was always out of breath and huffing and puffing, even when I was slim and in the low 50s and carrying around an extra 18 or so kilos.
Recently, I became less conscious of my breathing. I stopped counting and I found my natural rythmn which is about 3 counts in and 2 out and I no longer get out of breath (unless of course i pick up the pace significantly or hit a big hill) and as I said above, my legs give out before my lungs do. Can't believe it took me so long to work this out!
I don't know exactly what my point is, but maybe experiment with different counts
But I'm sure you'll find your natural rythmn anyway as you continue to train and pick up distance and improve your times.
I've always wanted to be a runner -- it really appeals to me -- time to pound out any agression, have your thoughts all to yourself, see yourself rapidly improve -- but I've realised now that I'll never be very good at it, no matter how many copies of 'Runners World' I buy
Just keep moving! And don't be lazy...
SW: 74.3kg - 1/1/09
CW: 71.1kg - 3/5/09