What ways can i boost sex drive other than eating well, sleep, stress relief and exercise? can being underweight affect it? i'm 5'4" 106 pounds.

Possibly: If you are amennorrheic (not having your regular monthly period) because of your low weight then it could certainly affect your libido.Nutrition and exercise are always keys to optimal health and self-esteem. If those are not your issues you might consider asking your doctor for a referral to a therapist who could address the sometimes complex issues involved.

Boosting sex drive: Make sure that you're not exercising too much. You are a little underweight - and excess exercise will first raise cortisol and then lead to a cortisol deficit, where you can't make adequate sex hormones precursors. Testosterone is the "sex hormone" in both men and women, and in women is made from the ovaries as well as from the adrenals. Also make sure you are not too low in cholesterol.