Anniversary dates, especially the first are so incredibly hard. It looks like you did some really sweet things to honor your Alex, and help you cope with the sadness.
I had some anxiety issues. Sometimes it was waking in the middle of the night in a complete panic. Other times it was due to a situation. What you have been through mentally, physically and emotionally is incredibly traumatic. Anxiety can certainly be a normal part of grieving and can hit you out of the blue. I'd suggest talking with your physician and letting them know that the meds you have been prescribed so far aren't helping you. Perhaps there is something else that can be prescribed that will help. Not sure if you have considered counseling, but that might help give you some relief.
Please take good care of yourself...wishing you peace and healing.
Rosemary - 47 - Central, PA
Momma to Kayleigh 8/25/88 - 36 weeks
Elliott 8/29/04 - lost at 20 weeks due to severe PE/HELLP
Proud Grandma to Max Allen 10/19/10.