5 ft and size 12, since you are American then yes, you were probably overweight by almost every measure, including if I was just looking at you. Unless you mean you were a size 12 top because you have very large shoulders and breasts. Or, maybe a 12 to fit your hips, but always have to take in the waist on pants. Eating a lot of healthy food and exercising is great, but if you eat too many calories of any food it gets stored as fat in our bodies. That’s just how the mechanism works. Some people hold the fats in better places than others, which does affect health from what the studies say. Also, some people have more stuff clogging up arteries, fat is held in different places on the body depending on genes and other factors. Now, I say overweight, but you might have looked very average or normal weight.
I’m 5’6” and when I am a size 10 I feel overweight, although I don’t feel I technically am. I’m average in the curvy area, c cups, average hips, but I hold a lot of weight in my stomach. Someone else my height and weight might be distributed better, more curvy, less stomach fat and be much healthier, but if they were a 14 I would say they probably are overweight. At size 10 I also feel I look like an average/normal woman in her mid 40’s. Even at size 12 I think I would look average, but that is statistically average, we see women that size all the time in America, so it looks average/nornal.
As I said above, clothing size for women is a terrible weight to discuss weight though, because vendors size so differently and vanity sizing has increased again in the last ten years. I also said science is finding that a little overweight for older people seems to be protective and healthy, and maybe they will change some of the tables eventually for people over a certain age.
Are you saying all your numbers were good like sugars, choesterol, blood pressure, etc? I don’t doubt it. We probably don’t know what the inside of your arteries looked like or how well your body was fighting off cancer that sort of thing. When I was a skinny 16 year old I still had very high choesterol. Genes can really screw you. My cholesterol is the same when I am 130 and 150. The only thing that affects it is how much cholesterol I eat. One of my water aerobics instructors had a scare and they did an angiogram. She was overweight by anyone’s terms I think, easily a size 16 or 18, and held a lot of weight in her stomach, built like a box, and her arteries were perfect. I’m so jealous of that.
The weight measures for health are just averages and each person as an individual might not fit into the average.