A rough sanity check for light boned women is 100 + (height in inches - 60)*5. That gives you pretty much the numbers on a doctor's height and weight chart... and that puts a 5'10" woman at 160 lbs. It's fairly reasonable to have around a +/- 20 lbs variation around that estimate (tho that still leaves some heavy boned women overweight on paper and bordering on underweight in reality).

There's really no substitute for knowing your own body tho. If you've historically been healthy at 155, or 170, and your measurements have changed, then your current weight probably isn't ok.