getting off of Depo

So I've been on depo injection for 14 years. However, my migraines are becoming unbearable when my shot is due [every three months] and when I get my shot. I was missing a week of work every three months. I'm wondering if anyone has had this problem? Or has any advice about coming off of the shot. Weight gain? How long until you got your period? Any help would be appreciated! :)