+1 on the previous advice. The brand of chamois cream I use is Hoo Ha Ride Glide. It was made specifically for women and is available in a fairly large tube and also in small packets that you can keep in your bike bag or pocket to reapply during a ride. I am prone to contact dermatitis but have not had any allergic reactions or other problems with it. I use it before long bike rides and will also use it as a moisturizer after riding if there's any irritation. As with any skin product, I tested it on a small patch of skin in a relatively sensitive area (forearm or stomach) for a couple of days before using on a larger area.

Good luck!