Confused - How do i Do I am eating the Right amount Per day?

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Confused - How do I Do It? I am eating the right amount Per Day? How do i Know I am giving myself the best chance of losing the Max i can?
I was wondering if anyone could help me.... IVe been on MPF since March time (on and off) - But have stuck to it for the last 81 days in a row! Im a bridesmaid abroad in 7 weeks and i really want to get back to my weight i was a year or so ago so i can take all my holiday clothes away!!
However I am a little confused at how I should be working out my daily goal? My BMR is 1346 Cals. Should that be my goal?
I am trying to make sure I am eating enough but not over eating ? - Which got me in trouble in the first place.
Diets can be a confusing world!!
If some1 can help that would be great as i feel like im being really stupid!! (runs and hides under her desk - in case i am being stupid)
Thanks!
x