Low sexual desire may have many reasons. I need to know more about your rearing, early sexual experiences and fantasies etc.
Many women do not like oral sex. You can discuss your preferences with your husband because this may be one of the factors which might be putting you off.
To increase your desire you need to spend good romantic time with each other. Discuss your turn on and turn off with each other. Visual stimulation in form of photographs, movies or fantasizing can help you getting excited.