What should my weight be?

There is no exact anwer because you can have 19-22% bodyfat at a lot of different weights. For example, I'm 5'5" and roughly 23% bodyfat but I am also pushing 160lbs because I have a significant amount of muscle. You could also be 125lbs (like @carrieous suggested) and be within your ideal range of bodyfat too.

What do you weigh now, and what is your BF%?
If you are within a normal bodyweight you may have better results by starting a progressive, compound lifting programme while eating at maintenance or just above. A higher protein intake would help too.

Cheers, h.

There are many websites and resources that'll be able to calculate your 'ideal weight' based on your frame size, height, yada yada yada. I used to go by these to determine what my 'ultimate goal weight' should be. Because I'm short, I technically should be around 105-110 lbs to be 'perfect'. I'm around 119 - pretty far off the 'perfect' mark and you know what? Whatever.

Also - many of these 'calculations' will vary tremendously from site to site, not to mention your scale is going to dance around all the over place due to normal fluctuations. (I only have to LOOK at cheesecake and I've gained 2lbs ). My opinion? The best tool for you is your mirror. Start a progressive strength based work-out routine if you can as this will certainly help the process.

There are some girls I know that weigh 120 lbs and have little belly pouches and love-handles still (Yes.. I mean ME!) and there are friends of mine that weigh the same but lift heavy and regularly and look at least 10-15 lbs 'lighter' than me. Mirror is best