Congrats on the weight loss! That's awesome
As someone with multiple food allergies, eating out usually isn't an option for me at cons. The short answer is you'll have to bring your own food (or pick up groceries once you arrive).
If you have access to a cooler or mini fridge in your room, you can store your own perishable food. I typically stock hard boiled eggs (for breakfast), lunch meat, cheese, and veggies. I'll also purchase a few non-perishable staples like crackers and granola bars.
On the con floor, I always bring water and snacks, so I'm not tempted to purchase the over-priced food when I get hungry. I usually bring trail mix, baby carrots, protein bars, beef jerky, and fruit while I'm walking around. Hope this helps a little bit.
Hope you have fun at the con!