Dear OP,
Congratulations on making it through life without falling through the many pitfalls that are out there.
You moved 5 hours away from parents and now they are still stalking you.
It is hard being a parent for over 20 plus years and they fly away.
By now they should have moved on after that empty nester syndrome.
Issues are not really on the table, as you know. Talk with someone if you wish about them.

Trust me anything you suggest will not make amends to their complaints. They want what they want and that is not fair to you. You are everything a parent wishes for, you are self sufficient woman.

One thing with my daughter was call just to say hello/or goodnight. Holidays are less important. Quality time versus Quantity. Yes you can say no without the guilt.
My daughter and I are relearning. It takes time.

They have to find things they enjoy and are time consuming.
They have a new life to experience, if they choose.
They can't live vicariously through you.
Guilt will only drive you away.
The more you stand up for yourself and what you want and what makes you happy should be a good starting point. You set the boundaries without guilt and you will feel better.
H.