Is Taking Low Dose Of L Tryptophan Safe During Pregnancy?

I have an anxiety disorder. I started taking L Tryptophan at night and it worked like a miracle. I am about 4 months pregnant and haven't taken it since the start of pregnancy. I am don't like the way I am feeling emotionally and am nervous about the horrible downward spiral that comes after delivery. Can't I just take it in a low dose like 500mg so that I don't feel like yelling and crying at a moments notice?