This kind of problem is often a cover for something else. You had good reasons for not inviting more people. You probably didn’t want to have so many more people than your fiance did at the wedding. It was probably wise not to invite coworkers who are not close friends. Doing so might have been awkward for them. How do they decline to come — even if they want to — when they have to work with you every day? And you made some decisions about priorities when you were pressed for time. This all makes sense to me.
What doesn’t make sense is your obsession. I think you gave both of us a hint about what is going on in your last paragraph. You really want to switch careers but can’t justify it on rational grounds. Maybe you are unconsciously creating “irrational” reasons that will push you to take the risk and find a way to go back to school. I suspect that if you start taking steps to do what you really want to do, your obsession about the wedding will fade. It’s worth a try.
I wish you well.