I have 3 ds, there are 8 years between each one 16, 8 and 19 weeks, I've found the age gap quite nice, they are able to do things for themselves so don't need your constant attention when your feeding the baby etc and they love helping with the new baby, both of them have fed him, play with him, comfort him if he crys and im making dinner, I think it's probably easier than having two little ones needing to care for ( Ill find out next year if this is true though as im pg again! )
Surely it depends on what type of illness you have had for that length of time as to whether your body would cope. Have you asked your GP? 8 is not a big age gap at all. Go for it if you are feeling better and want another baby.