BMI - An indication of Health

Because of Weight Watchers, I knew that 160 was the top of my healthy range for my height range, but never paid much attention to the detail of this until coming across http://www.hc-sc.gc.ca/fn-an/nutrition/weights-poids/guide-ld-adult/bmi_chart_java-graph_imc_java_e.html, a government website. I like this site because the other 'trackers' always want to round your height. WW says I'm 5'7", Ticker factory says I'm 5'6", but I know I'm in between these - at least I used to be 5'6.5". If anything, I'm more likely to have lost some height and will need to measure to be sure.
According to the site, and using 5'6.5", at my highest non-pregnancy weight (around 189 before I joined WW) I was just at 30BMI, which is considered Obese Class 1. By the time I joined WW, I had dropped to 29.6, the top of the overweight range (Ticker, above, still had me at 30, shorter, and technically obese). 24.9 is considered 'normal'. If I am currently 26.6, still 1.7 BMI to go. In terms of weight that is anything under 157lbs. So, I think that after I reach 160, I will need another mini-goal of 156.8.
One other thing, healthy is anything 18.5 and over. WW has the bottom of my range as 128 and, even at 5'7" appears to be using 20, vs 18.5, as the cut-off. This gives an extra 2.5lbs to my height. But should I REALLY worry about whether or not the low range is 128 or 125.5? Not likely.
Of course, all of this excludes other health factors such as muscle vs fat, bone structure, etc. and knowing that 130 was too thin for me when I was 18 and likely still is (that involved 8 hour shifts over a fryer for 2 months at KFC and is another story).

Maybe I should just concentrate on staying OP today, plan for the weekend, and see what happens next Wednesday. 160! AND BEYOND!

Have a great long weekend!