Luckily, my company is very IP-friendly, so that makes trainings and conferences easy, but client functions can be a whole different ball game...very similar to your situation!
Sparkling water or soda water with lemon works as a good cocktail substitute. Dinner can be the easiest, since most catered meals include a protein choice, a vegetable choice, and a salad. Obviously, you need to avoid anything on the restricted list, anything drowned in butter or dressing, etc...sometimes I end up eating the protein choice (seems like it's usually chicken or fish) and just poking around at the rest. Lunch can be trickier since it tends to involve sandwiches a lot, but worst case scenario, you can just eat the turkey and lettuce, not the bread.
And definitely take a ready-made shake (or two) with you...they're a life-saver. Better to ingest an extra 100 calories and 20 grams of protein and not be hungry than go OP. Also, have a water bottle on hand at all times...you'll stay hydrated and keep your hands and mouth occupied if you're feeling tempted to stray. Either way, you got this, and congrats on the 15 lbs!