Although frustration may have set in, you're doing the right thing by questioning others. I also was gaining a little weight recently and it wasn't until I sat down and analyzed that I got a clearer picture of what was causing it. I determined it was water weight and muscle addition in my case, but I know that my stress is contributing to a cortisol increase as well. Ugh.
Track your actual intake of everything you eat, how much sleep you are getting, what your workouts consist of and how often, etc. and report back to help diagnose in addition to what others have suggested.
Don't lose the faith!
Resolve to Evolve