Male (35) with female (44) insecurities about future

I'm a 35 male with a 44 female. We have been in a relationship for 6 years. She is a amazing human and love of my life.

For some reason the last year I have found myself getting insecure about the difference. Notice I'm zoning in on physical faults, getting worried about retirement and how we approach it as I don't believe I'll be able retire 9 years earlier.

I really fought to get stop overthinking this the last year but it persist.

I don't know what to do, I want to be able to move forward with her by my side but I feel I'm in turmoil. I don't know if my feelings are valid or just anxiety.

I want this to work so bad but I want to be sure going forward with happiness and certainty.

Any advice appreciated thanks