Hey there!
I agree--one mess up does not ruin a weight loss plan.
That said, you can't be going to MacD's all the time because your daughter likes a treat. That's sort of setting yourself up for bad eating. If you do take her, don't eat there yourself. Sorry, that's the only way I see it, because if you add up the calories in what you ate there, I think you'd see their food is way over the top...
Find better treats! I don't go with egg white omelets as a "treat" myself... but there are many better choices for both you and your daughter.
Jay