Running at a slower pace than your natural running place will inevitably feel odd at first, but if you want to master it, it's just a matter of practice - shorten your strides and just hold yourself back (although I agree that if you are breathing ok and able to sustain the pace for the distance, you don't really need to slow down). I have to slow myself down to the pace of the runners I'm out with, and as I take a wide range of abilities I've had to learn the discipline of running at paces which aren't natural for me, but it can be done.
I coach total beginners a lot, and I often have one or two who complain that the pace I want them to run at "feels unnatural" or "isn't comfortable", yet they simply can't sustain the pace they want to run at. I run alongside them and insist they match my pace so I can slow them down, and after a couple of runs like that they get it. You just need to build stamina first before pace.
As far as the breathing's concerned, if you could talk at all, say in short phrases, that'll do initially. If you really couldn't talk, slow down.