I think it's completely normal to feel as you do. I find that often people who have had to struggle with weight (like me) do not trust themselves. I've been on maintenance since Nov. 2011, and it took me more than a year into it to begin to trust myself. That first year, each time I would overeat, I would feel like, "Oh no! I'm going to regain all my weight!" But as time went on and I didn't, I realized that I really do have control of what I eat. Now, I trust myself 95% (there is still that 5% that panics occasionally). For example, the past month or so, I've been really bad about BLNs (bites, licks, nibbles). I mean, I could not go into the kitchen without picking on something. This week, I've vowed that NO MATTER WHAT, I will not pick. I've given myself permission to eat another meal if I'm hungry, but I will not pick. So far, so good.
The point is that you gave yourself permission to eat that meal. You did it. What's wrong with that? Enjoy it and move on. In the scheme of things, you've done well by planning out that meal. Think of how much you might have eaten before your started calorie counting.
Clothes Sizes (not lbs):