Suggestions while using Fitbit Flex and MFP

Hello! I have just begun my weightloss adventure 2 weeks ago. I am getting married in September and would like to lose about 35 lbs by the end of June, which I know is a stretch. I am making progress with what I am doing currently (staying around 1200 calories daily or more on gym days and generally moving more throughout the day, as well as eating more nutrient dense foods and drinking half my body weight in fl. oz. in water daily).

However, I just started using the Fitbit Flex at the beginning of this week and I am very confused about how I could possible have burned that many calories from just walking around (4-500 daily). So to be safe, I haven't been allowing myself to eat those extra calories. This did concern me though that maybe I need to up my intake. I want to build/tone muscle and lose fat, not burn up the muscle I do have. Any suggestions on how you handle your "extra" calories would be greatly appreciated. I have a basic idea of having a calorie deficit and I was wondering if this is the "deficit" that I need to be adding up to each week.

Just a little background: I have MFP set to sedentary and to lose 1.5lbs per week and I have set the fitbit to the same goal. I am working out at the gym 2-3 days a week and I religiously log my time spent workingout and the start time so that I am not getting double calories burned. We also just purchased a food scale and will begin using that for everything to make sure we are measuring things accurately.

I would greatly appreciate any advice. Thanks!!
Also, please add me if you are in a similar boat and need someone to help you be accountable! I definitely need more of that.