Here is the truth about adults: we are all three years old and we don't know what the heck we are doing don't be fooled by those who have "every thing sorted in their life" I can tell you it's all appearances...anyway..I mean: many topics in your post!

First, eating shrimp and green is fine, even with the dressing. You are still on the horse! I was never counting calories everyday, my main focus was to eat enough protein. And look, I lost 100 pounds. So it must be working somewhere.

We are social animals : we like to eat with our peers. You can perfectly prepare your food and eat with your colleagues (I did that for years).
But it's true that obesity is "contagious" and people who over eat tend to influence others around. But look, you could be the one influencing the others to eat healthier!
And it's not because you saw people failing around you that you're going to do the same. We are all different and do learn from our mistakes.

Plus you have your sleeve working for you right now. Enjoy the honeymoon and Stick to the plan: protein, 1/2 cup per sitting, water. Don't go hungry, bring nutritious snacks. The key is to really plan your food and find healthy things you really love, it will be easier.

I have a collection of lovely lunch boxes, thermos, bento boxes etc... It did help, not just me but also my youngest kid who goes to school with a lunch box (we live in Asia right now and here carbs/rice are everywhere and carbs are not good for my kid either).
My husband prefers to eat in restaurants during the week, and we currently don't have a cafeteria at work. But in a few months we will. I will still bring my food at work even if we will probably have a cafeteria with lots of choices available (don't care what people think, I'm the one who's important here). I prefer to know what I eat and eat mostly organic when I can.

On an other side, look at what kind of money you would be wasting when "eating out". Yesterday we had a family lunch in a restaurant. I was able to share my food with my family (basically my husband ordered a salad and had 3/4 of my main with it ) , but if I'm out during the week I can't do that. It's a big waste of money. Try to work out how much money you will be saving and plan on doing something fun with it for you. That would give you an other goal to achieve. Little by little it will add up. You will be surprised of the final amount. I was. It's huge the money we waste eating out!

Thank you!

I bring my lunch to work every day. It keeps me honest. I can still eat with friends and eat my own stuff. I always keep my desk stocked with things to help me avoid temptations. I have beef jerky, nuts, tuna, pumpkin seeds, protein bars etc. If someone brings in something sweet I can have a bite of peanut butter chocolate protein bar and it helps me take the edge off. If someone eat something at their desk and I smell it and get hungry I will have a piece of beef jerky or some nuts. I also try to walk on my 2 20 minute breaks to avoid sitting too long. It is ok to eat healthy options with your friends if they're available. I agree with Sandra, it is only falling off the wagon if you are eating things you shouldn't. Having some protein and veggies is fine...even if they didn't come from home. You got this!

Thank you!