I have missed 4 periods and counting due to my eating disorder so i was just wondering how many you have to miss to be infertile?

Good question!: ...But how do you know that your amenorrhea (missed periods) is secondary to an eating disorder? At 44, you could simply be starting the menopause, since 45 is generally thought to be the average age of onset for that. Even with sporadic menses, it does not necessarily mean that you are infertile. It's a good discussion for you to have with your ob/gyn! they may need to rule out something else...