What should my daily calories be??

I'm just a bit confused and want to make sure I am not overeating what my target daily calories should be.... when I use the CC tool and some others that I have randomly googled it tells me my resting BMR is around 1950 so I have set my daily calorie intake at 1450 (I haven't been getting to the gym as much as I'd like, I work about 13 or 14 hours a day - always opt for the stairs and walking though).. But even without working out thats still a sedentary deficit of 500 a day.

After I weighed in after a month I had only lost about 2.5 lbs, so I googled a few other BMR sites and some are telling me that my resting BMR is closer to 1700, meaning I'd have to bring my calories down to 1200. What is right, what should I be eating/doing differently??  Any advice helps, thanks!