As Jo*mar suggested, the medications that you take are quite possibly to blame, but I did do some checking for you, from the perimenopausal point of view.

The most basic cause of low sex drive in women is hormonal inbalance, which comes in many forms. Progesterone is crucial to libido, and the natural fall in its production during perimenopause can wash away sexual desire all by itself.
http://www.womentowomen.com/understa...sofdesire.aspx

Both physical and emotional factors can lower sex drive.

The most common physical one is hormone inbalance. When hormones are out of balance, other symptoms also arise. These include hot flashes, insomnia, fatigue, mood swings, and weight gain. Once women get their hormones back in balance, they usually get their desire back as well.

Another factor is stress.

The body naturally puts survival ahead of pleasure. Your over-burdened adrenal glands can rob your body of the building blocks it uses to make estrogen and testosterone, which are vital to desire and sexual response.
http://www.womentowomen.com/sexualit...menopause.aspx

Nutrition and diet also affect libido. Not only does chronic dieting lead to hormonal inbalances, but also has an inpact on energy levels and self image, which in turn leads to loss of libido. Low fat diets cause havoc with our hormones, as fats are needed by the body to manufacture hormones such as Progesterone, which is the hormone needed by our body for sexual desire.