Hi Angela,
It's really hard at first, but it does get better, honest
. If you can run 12 minutes already before you start to struggle, it sounds like you're doing really well!
If you're struggling with breathing, you're probably trying to run too fast. It takes a while to build up aerobically, so just slow it down a bit and you'll probablt find you cn keep going for longer. Also, if you start struggling just walk for a bit then try running again after a while. A lot of people build up this way and I certainly did.
At the start it's time on your feet that's important, not the speed....that will improve with time.
Good luck, keep at it and keep coming back for encouragement 