Yeah I know a girl who is 5"1 and 130 something. ACtually, a few girls like this. You would never be able to even tell! Even though they are at the high weight range end, they are both built very hourglass-big t*ts, big ass, muscular thighs, little waist. They don't wear a big clothes size, they look firm and in shape and guys LOVE their bodies. Even my doctor said that sometimes your body type can add extra pounds that aren't anything to be concerned about, like big boobs. Because big t*ts/ass are heavy!
At 5'0 to be healthy you really should be between 95-115. 140 for someone who's 5'8 isn't a big deal but at 5'0 it's not healthy. You're probably not like morbidly obese or anything but you're definitely overweight.
It depends on your body type. The ideal weight for a 5'0" female (according to BMI charting) is between 90-110 lbs. But even that I wouldn't necessarily trust, because it depends on your build and genetics.
Don't worry too much about weight. Exercise regularly, eat well and get to the weight you like best. Don't focus too much on averages and whatnot - they aren't accurate for everyone. So long as you're healthy and like how you look, your weight is perfect :)