No, I don't think you are over-thinking! It's perfectly understandable to feel the way you do!
I myself am retired now, but was a Ward Sister in a surgical unit before I was out of my 20s. What I found back then, and it was in the 1980s, before I had my own 2 children, was that some adult children were very concerned about their ill parent, and made regular contact by telephone to enquire after their well-being - this was in the days before everyone had mobile phones! Other adult children either didn't make contact, or did so only on very rare occasions!
Fast-foward to the future, and I am now retired from nursing, and my 2 children are grown up. My son who has a disability still lives at home with my husband and I. My daughter left home in 2010 to return to our hometown 50 miles away, as she had always hated it here and never settled. She has just given birth to our first grandchild on 12th January! The difference between my 2 children has been apparent since they were both small. I had to retire early from nursing due to illness, and this has worsened in the 10 years since I retired. My daughter is very dismissive of my health issues and treats me as if I am some sort of nutcase because I suffer from depression! She only makes contact with me when she wants something! My son, on the other hand, has always been kind and caring, goes out of his way to help me and his dad with household chores and shopping etc. Both children were brought up in exactly the same way!
My husband defends my daughter, by saying that when children leave home they often make minimal contact with parents - he is the youngest of 3. I myself am an only child, and lost my father to cancer aged just 54. My mum fell apart after his death. My husband and I moved house to be closer to her and in spite of me working full-time in a very demanding nursing role, I got permission from my line-manager to phone my mum from work every day to see how she was. My mum developed cancer herself within a few years of my dad dying and passed away aged just 62, younger than I am now. I was always very close to my mum, she was my best friend, and I know that I did everything I did to make her last years as comfortable and worry-free as possible!
My husband rarely bothered with his own mother and when she was terminally ill, it was me who looked after her, did her shopping etc. However, my husband did look after the children to enable me to do this!
I hope you make a speedy recovery from your operation soon, and that your children do get in touch shortly to see how you are! Sending you healing hugs. ??