K.S.
Babies younger than 1 year rarely wean themselves!
What you are experiencing could be caused by a myriad of different things - a potential "nursing strike", she could be teething, you may be experiencing a lower supply due to your menstrual cycle, or she could have just been distracted - all these things could cause your baby to nurse less in a day.
Please don't feel as if you are being selfish - breastmilk is the BEST thing you can do for your daughter AND yourself - if anything, it's the most selfless thing you can do. Bonding aside, you are helping her immune system, providing her with nutrients she cannot get anywhere else, helping to boost her IQ - just to name a few of the many, many benefits of breastfeeding. In addition you are providing yourself with some protection against diseases such as breast cancer.
Check out "The Nursing Mother's Companion" if you haven't already - it's a great resource. And remember, while our society IS making strides toward becoming breast feeding friendly, we definitely need to come a long way. Be careul what advice you listen to - go with your gut and remember that nature doesn't usually make mistakes.
Best of luck - your daughter is one lucky little lady to have a mama that cares so much!