Hi there Snowbunny and welcome to the forum!
It does sound to me like you have made a wise decision and congratulations in being mortgage free.
Yes I do know exactly what is is like - having done the same thing three times. That is, selling a real estate asset and seeing the price skyrocket shortly after. I am talking hundreds thousands of dollars!
What I found helped was to remind myself that at the time I was happy with the price I got, and that the asset I stayed with or purchased, was also going up in price. To dwell on 'What if?' is a waste of time as it has happened and we cannot control the past.
I even got to the stage after one sale of driving past the block I sold which was waterfront, and bemoaning the fact that I wouldn't be living there any more.
I think that is called 'Seller's remorse'. The best solution I found was to ask myself if I still wanted to be active in real estate. The answer was yes, as I enjoyed it. So I now look to the future and keep an eye out for opportunities that might interest me - at the same time real estate agents are asking me if I want to sell my current home.
I'm a lot more careful now and risk adverse, but still find it fun. Doing research on property value trends is fun.
Maybe your anxiety is just a phase you are going through. Wait a few months and when real estate prices drop again as they are bound to, you might congratulate yourself in the price you got?
Anyway I hope this little story has helped a little Snowbunny - you are in a rare situation of being mortgage free, something lots of people would be envious about.
So it sounds like you are very smart and a high achiever- be proud about that!
Happy to chat more. All the best, The Bro.