The only thing I can say is that in that another 90 days or so will mark 2 years we lost our 17 year old. 5 months after we lost him, we lost my 88 year old father who had lived with us for 4 years.
Sad to say, I know from experience that the grief is nothing alike on losing both and it is a "club" who I would never wish on anyone.
When our other son turned 18, he joined the service and freaked my wife out a little bit, but very proud in the fact that he wanted to follow in his family footsteps, particularly his grandfathers.