Underestimating and calorie goals

evanescent_jasmine

Okay so I know it's pretty impossible to accurately measure food without a scale, but since my family think I'm being too obsessive already there's no way I can use a scale here at home. I just eyeball my portions based on the general internet consensus (3 oz of meat like a deck of cards, etc) and hope I'm not too off. Even so, I keep in mind that I may be wildly underestimating.

Now then, I set my goals to eat around 1200-1400 cals a day. My BMR is around 1600. I've read a lot of articles and topics here that say I should never eat below my BMR, but I'm reluctant to aim for 1600 when I might well be eating 1800 and never know it. I've been losing weight steadily for the past months and don't want to ruin that, but at the same time I don't want to ruin my metabolism. I don't feel hungry or deprived or anything and occasionally I even plan a spike day, but is that enough?

Thoughts?