Those are some really great words of advice Judy.
To the OP, I have had some similar experiences in my life. My father died from surgical complications only 11 months after his younger sister (my aunt) committed suicide. Then less than two years later an uncle on my mother's side died in a car crash. He was a long haul truck driver and was in the sleeper talking to his wife on a cell phone when his partner rolled the truck and it killed him. This all happened from the time I was 11 until I was 14 (I was 12 when my father passed away). Looking back, I feel I spent a large majority of my childhood grieving and attending funerals.
Growing up on a large farm, with an older brother and a younger sister, my mother decided she wanted the farm life to be an option to us three if we so chose to take it over once we grew up. She stepped up and took on all of the farm work upon herself (no small feat). Not only did this mean my mother's free time became non-existent, but the three of us had to grow up quickly and basically learn to take care of ourselves and each other. Most of my summer vacations from school growing up consisted of driving farm equipment for 12 or more hours a day every day of the week doing as much farm work as I could so my mother wouldn't work herself into an early grave.
I am now 27 years old, have successfully put myself through post secondary receiving a Bachelor's of Science in Engineering (thanks to a LOT of student loans which I will be paying off for a lot of years to come).
Going through these experiences does make a person think of the hardships people go through, and if I would be able to put my kids through the same grief if I were to die at a young age. But I also believe that I am the person I am today because of these experiences. It has instilled in me a hard work ethic, good morals, and to never take anything or anyone for granted.
Try not to put so much emphasis on 'what else can go wrong' in the future. I did this for a long time which caused a terrible bout of depression. As hard as it may be at times, you must look to the good in life. Spend time with the close friends you have, or your older brother and create lasting memories with those you hold dear.
As for being a ticking time bomb, or passing things on to your children, this is something that you and your partner can discuss together when you have the 'do you want kids' talk. Having someone who you can be open about these issues with may be very beneficial to help ease your anxiety about it. No need to stress yourself out over issues that may not come to fruition for a few years.
Sorry if my rant was a little unorganized. Sometimes it is hard to gather all your thoughts in an organized way. I know the world can feel like a lonely place when so much has been taken from you, but know that there are others out there like yourself, and if you ever want to talk about anything, feel free to PM me.