What should I do when my grandparents pass away ? ?

Create lasting memories of them now.  When they are gone, you'll miss them and be heartbroken.  However, you'll be able to remember when...

So what can you do now?  If possible, go to visit with them.  Ask your Grandma to teach you some of your favorite recipes.  Have game night (boards, cards, horse shoes, whatever).

Ask each of them to tell you about a vacation they went on when they were younger, or life as a child or teenager.  What do they do for fun.  Write it down.

I asked my grandparents (who grew up on farms in the 20's/30's) about their childhood.  They refused to talk about it.

My grandmother did volunteer work.  I joined her.  I went to my Great-grandma's house, spent the night and played card and board games with her, my mom, and sister.  We created memories.  Even though they passed away more than 15 years ago, I still miss them.

I get together with my cousins and we talk, remember when we played pictionary? Remember when we got to sit at the adult table?

As far as who you are?  That will change along with your goals.  However, go ahead and write down all the goals that you'd like to do.  Then see which ones you can do now.

It used to be that a person would learn a trade or go to college, and would do that job for they rest of their life.  Few young people today stay with the same career.

not much you can do about it

Well, it sounds like you should talk with a therapist, because now while there is alive you should try to get a better understanding of your wants and needs.

Poor confused troll.   Have a French Fry and it will all be better.