BMI is not in itself a good measure of your body. An NFL football player can be obese on BMI because muscle weight is not factored in, just total weight. That said, for the rest of us it is a good place to start. Statistics show reasonably healthy males with 15 to 18% body fat and healthy females with 20-25%. You need to use other methods to measure that. But, for now, if you are losing weight at around 1-3 pounds per week, you are doing alright. When have you reached your goal? When what you are eating (in calories, but also nutrition) balances out with how much energy you are burning.
When I was nearing my goal weight, a coach told me that my body would tell me when it is done. That proved to be true. I had kept the same caloric values going in for a year, and my body reached a point where I stopped losing and leveled out. I have kept that excess weight off for more that 8 years now.
I HAVE NOT STOPPED EATING THE WAY I LOST THE WEIGHT. I still eat the same way today. I still keep the weight off and I still eat a nutritious and well-balanced diet.
For the record, I saw an old penny scale that used to stand in front of the local drug store. It had a chart of acceptable weights, based on height and gender. Back then, a 5' 10" male was rated for 150 pounds or so. Today, we think that is too small. Is it really?
There are scales today that can measure electrical resistance while weighing you. They can tell you what body fat percentage you have (forget the BMI).
Keep doing things right, measuring and recording your food intake and exercise, avoiding the 'crap' that masquerades as food, and turning down the out-sized portions that you get offered by well-meaning but misguided friends and family. You will get to the right weight for you. If you are paying attention to the details...