Should I eat more, or less?

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I switched 3 weeks ago from WW because it's expensive and I was holding onto the same number on the scale for 6 weeks. I lost 1 kilo in my first week using MFP and eating my BMR- about 1600 for my height (163) and weight (80 kg). Well, in the past two weeks, I've gained that kilo and 2 more back! I know I'm eating about 400 more calories a day than I was with WW, but I'm confused as to if I should be eating more or less. I do cardio 2x a week and weights 3x and I keep a 50/20/30 carb/protein/fat ratio that I'm working on whittling down to a 40/30/30 ratio. I eat back the calories I burn on cardio days and have a protein shake on weight days right after I leave the gym.

I know if I'm not eating my BMR plus 3500 it's probably not fat that I'm gaining, but I HATE seeing that number go up!