It's complicated. There are many reasons why a woman may have decreased sexual desire. Some of these include: hormonal deficiencies or imbalances, underlying medical conditions like hypothyroidism, depression, fatigue, life stress or conditions which cause discomfort during intercourse. I suggest a visit to your ob/gyn to discuss how you're feeling and to see if you can identify the possible issue (s).
Lack of change. You may be experiencing lack of change and excitement and spicing to your sex life with your husband; try different and new things you never done before more foreplay more surprises. And good to check your testosterone level.