The approach for your lack of sexual interest or low libido would be to identify the causes among these;
1) Hypoactive sexual disorder
2) Sexual aversion disorder
3) Female sexual arousal disorder
Women often present with the complaint of loss of desire but with little awareness of how, when, or why the problem occurred. With the time, this foundation of sexuality can be altered by changes that affect many aspects of sexuality and sexual function.The distinction between drive and desire is essential for any of the above problems to be assessed properly. So a blood level measurement of various hormones is an essential component of the management.
The treatment is done on the following main lines;
1) individual or couples psychotherapy/sex therapy,
2) hormone therapy if any abnormality is found
3) tibolone, a synthetic selective estrogen and androgen modulator
I can understand that this is not easy to talk about these problems with a doctor whom you know for very long. But this would be the doctor who would be able to handle it in the best way as he / she is close to you and family. So just discuss your problem without any hesitation. An hormonal profile especially thyroid, prolactin, LH, FSH, estrogen, testosterone etc should be done. This may help in ascertaining the cause. If these all are normal; you may need some counseling session and other psychotherapeutic medications.
Please feel free for your follow up questions.