I agree with you about there being a need to worry. I would be worried if I was in your situation - there are a number of things about it that would cause me concern.
Ok - here's what I do to deal with problematic emotions. I'm not particularly insecure but I do have a tendency to worry and be anxious about things that may never happen.
So I assume that not a single one of the relationships I currently have is going to last for my lifetime. The individuals involved may die or they may choose to follow a path in life that means they are permanently or temporarily distant from me. This counts for friends, partners and family relationships. I take loss as a given fact of life (I think it is for the vast majority of us).
With that in mind, I make sure that I have things I can do to cope if something goes wrong. If somebody important is gone from my life. Running, walking with C, watching TV and knitting, having baths and reading and meeting friends for coffee/food/drinking, going to work all work well. I also - if things are going badly - give myself permission to not do anything else beyond the bare minimum for as long as I need to.
I also let myself feel sad. It's fine to be sad about losing loved ones even if it is just temporarily. I don't try to talk myself out of that or out of the worry that I feel over future loss. Those emotions are normal I think.
In my general life I make sure as much as I can that the things I do to cope are open to me should I need them. Stay fit enough to benefit from running and walking, keep some means of watching TV in the house, keep my job for as long as possible, maintain existing friendships and be open to new ones.
The other thing that I do is concentrate on the good things right now. What is in my life right now that I am glad I have. The things change but so far there has always been plenty to be glad about.
I feel that with a good range of things to do to cope with loss and a focus on things that are good, I don't get as concerned as I used to about loss. It happens and it sucks but it isn't the end of the world.