How tall are you? Did this weight gain make you overweight, or did it just bring you higher in the healthy BMI range?
As weird as this may sound, it could be that you just finished growing. Most women have one last "filling out" growth spurt in their early twenties, but it sounds as if you missed that. You could be having it now. As a very general rule, if you're not overweight at 18, it's actually not normal to be the same weight all the way from your late teens into your adult life. You might not get taller, but your bones thicken and you develop more breast tissue, more of the necessary fat around your hips, and even more blood. It's unusual for this to happen so late, but it might be a good thing, not a bad one, as far as general health goes. (Again, this is all assuming you're not extremely short. If you're only 5'0", then it's a different story.)
Is your doctor concerned, or did s/he just order the blood work to calm you down? The tests may tell if there's a problem. If it doesn't clarify things, the next step is a body composition test to find out whether those 10 extra pounds are fat or whether they're bone and muscle. Talk to your doctor about getting a bone density scan that also reports your body fat and lean tissue percentages. If your insurance won't cover that, there are other types of body fat testing (and sometimes there are inexpensive ways to get the bone scan), but if you've got decent insurance and you stress the fact that you've been dieting, it should be covered as a baseline for later osteoporosis testing.
| current weight: 132.0