Emily -

1) Hand held bioimpedence measurements can be off by +/- 4%...so take the number with a grain of salt. If you want a more accurate number, caliper measurements by someone who is highly trained, or submersion will be your best options. But, like others have said...it's just a number so it's probably not something you should put much stock in.

2) How you feel about your body is way more important a gauge. And if you think you need to tone up in the middle (I know what you mean..I faced this prematurely when I was on anti-estrogen therapy for an unrelated issue...my middle grew and it really, really bothered me)...there are things to do that do not involve weight loss. First of all, lift heavy. Much heavier than 8 - 12 lbs. The reason that you look different than you did 20 years ago is due to hormone changes and muscle loss. Fight it by lifting weights and get that muscle back. With your tiny build, there is NO WAY that you will bulk up. Only a very small % of women can (naturally) and chances are, you are not one of them. Secondly, have you tried Pilates? I know a lot of women who have really toned up the middle (especially women who aren't really overweight to begin with) by taking Pilates from a certified instructor. Combined with your current cardio program, you can see great changes.