Have you tried the IWB thing yet?
Most men find it comfortable and concealable, but women are shaped differently and it might not work for you.
I recommend you experiment with this position a little bit before you spend money on an IWB holster.
You can stick the pistol in a tight pair of jeans "Mexican Style" to see how it works for you. Put it in the same place and at the same angle that an IWB would hold it. Use a good belt to support the weight.
Now walk around a bit and move like you would during your normal day.
Does it lay flat against your body, or stick out? How does it fit under your arm when you walk? Can you draw it? Does it fit under normal clothes or will it require special clothing to make it conceal?
You might not want to run around out in public without a real holster securing your pistol, but you will be able to see if this mode of carry is suitable for you.
A woman's waist is higher than a man's, and her hips are rounder.(Thank goodness!)
This usually puts the pistol in a position where it's either sticking out like a flagpole or almost in the armpit.
Neither of these conditions is suitable for comfortable carry, ease of draw, or concealment.
For more info from a woman's point of view, look here.
http://www.corneredcat.com/Holster/straighttalk.aspx