Lack of Sexual Desire in Wife. Expert?

Married for 09 Yrs. I'am 07 Years elder to my Wife. We had a Wonderful Sex Life. After One and Half Year Had Child. After Two and Half Years of Marriage, Wife is showing almost NIL Sexual Desire. From last Seven years we do average Two-Three times Sex in a Year. This is leading to unhealthy Married Life. Reasons she quote are presence of Son and consciousness towards her career. We had Marriage Councelling for One Year. It helped in easing out tensions but didn't improved Sexual act much. She considers that it is only Men's requirements. She is a Computer Engineer. I'am am internally very frustrated. Can't discuss this topics on daily basis. I have to regularly masterbate. Please suggest solution. Shall we further consult Psychologist or Sexual Health Expert ?