I can relate. It used to be that I'd get a number...let's say 135 in my head and stick to that in H.S., but now that I'm double that age +, 135 is casket weight for me. Now...I just judge myself by bodyfat %. Right now I'm probably at around 19%bf, and my goal is 15-16% (I like ultra lean), but that is not to say I'm NOT happy where i am. I'm lovin it.
Also...everyone has their own "personal" goals. One woman may want more curves....another more of a "sporty spice" look, more athletic, another may want the Kate Moss look... so it's important for you to be honest with yourself as to how YOU WANT your body to look and aim for that as your goal....whatever the scale may fall upon.
I guess my point is don't judge by the scale. Every woman carries her weight very different. Some are more naturally muscular than others. Others naturally have higher bf% and must be 135 lbs to be lean. Others can be ultra lean at 160 lbs at our height. Go by your clothes, the mirror, pictures and generally how YOU FEEL you look.