Hello, The cause of the irregularity in your cycles could be the psychological disturbance or some hormonal disturbance. Pregnancy is less likely as you have had a normal period now. Xanax is not likely to cause a false positive urine pregnancy test. To rule out, you should take the blood test for pregnancy as it is conclusive. Please remember, the medication you are taking at present is not recommended in pregnancy and hence, if you contemplate pregnancy at this juncture, choose your medication carefully after discussing with your doctor. Hope this helps.