Just what others have said. I am a yeller too, I'm afraid
I totally agree that time to yourself (even just a little every now and again) refreshes you and keeps you a little more positive.
And I know that getting out and about with two can be hard... But there are some great playgrounds and change of scenes out there to be found! Your kids may not fight as much if you mix things up a bit. I know that if we go to a playground (it's somewhere that DD1 will always be happy to go, she has flat out refused to go to the shops before, even called my bluff when I said DD2 and I would go without her! She said, 'ok, I'll just stay here'. LOL!) then they are so tired and worn out when we get home DD2 sleeps beautifully and DD1 and I can do some craft or something fun and that keeps her happy for the rest of the day, even through the witching hour.
This of course doesn't happen every day. These are the good days. You are doing such a fab job being a SAHM and raising your great kids. Don't beat yourself up too much. We all understand how tough the parenting gig can be.