2 year services has been out of the window for at least 20-30 years. Males who are currently in their 40-60s were the age group (and era) in which 2 year military service was the norm.
Nowadays if you were born after 1980, it runs anything from 4 to 11 months. I don't think there's an official rule showing you how long your service is with accordance to your birth date, but this is just from my personal observation. My cousin, born 1989, did 11 months, the intern who sat next to me, born 1994, did 11 months. One of the kids on the cycling team, born 1996, is doing 4 months.
With your health issues, I most of here won't expect you to have to do too much time, but we can't guarantee anything.