I went from 300 to 173 and was a size 12. LOVED IT. I had no desire to be a lot smaller. This is a very individual process and you do have to figure out for you.
As for BMI, I would disagree that it's a good measure of health. It's simply calculated based on height and weight but doesn't account for muscle mass. So very healthy people can be considered obese based on this measure.
Also, BMI was not developed on research based on health.
"Belgian polymath Adolphe Quetelet devised the equation in 1832 in his quest to define the "normal man" in terms of everything from his average arm strength to the age at which he marries. This project had nothing to do with obesity-related diseases, nor even with obesity itself. Rather, Quetelet used the equation to describe the standard proportions of the human build—the ratio of weight to height in the average adult. Using data collected from several hundred countrymen, he found that weight varied not in direct proportion to height (such that, say, people 10 percent taller than average were 10 percent heavier, too) but in proportion to the square of height. (People 10 percent taller than average tended to be about 21 percent heavier.)" (From a good article on BMI history and use:
http://www.slate.com/id/2223095/
According to that article, the person who adapted this measure into what we know as BMI never intended it to be used for individuals!
"Keys had never intended for the BMI to be used in this way. His original paper warned against using the body mass index for individual diagnoses, since the equation ignores variables like a patient's gender or age, which affect how BMI relates to health. It's one thing to estimate the average percent body fat for large groups with diverse builds, Keys argued, but quite another to slap a number and label on someone without regard for these factors."
In fact, recent research indicates that people who are overweight are on average as healthy as those who are "normal" based on BMI, and in some cases, overweight individuals have better outcomes than "normal" people.
A long way of saying that if you're interested in health and feeling better and being able to fit in smaller clothes, a size 14 may well be a great goal for you!! You can always re-assess later.