I do sympathize with you, Helena, on several fronts. I grew up in a big city, so always had indoor cats as it was just way too dangerous to let cats out. In all the years of having cats since, I've always had indoor cats, or supervised-only back-garden cats, and have never had one who seemed unhappy or neurotic! We've always made sure we had tons of toys, carpeting on windowsills, cat-shelves and cat-trees and cardboard boxes and newspaper tents and you-name-it to keep cats busy and occupied as well as give them privacy when they want it, plus lots of play time as well. My beloved Lucia, who passed away this past 1 January, was always an indoor cat, with the exception that she would go out and hang out on my balcony in 2 of my apartments, but never tried to get out and away.
As far as your loss, I still miss my Lucia every single day and tears still come very often. I will never get over losing her, she was really like my little girl as well as my best friend. And of course she can absolutely never be replaced. But she was a stray when we found each other (she really found me!), and so a couple weeks after she passed away, I met Lily (Tiger Lily) who was in a cage in a small and money-strapped rescue, and thought she looked so sad and lonely and needed a home that I brought her home. I told the rescue she would be primarily indoor-only (she goes supervised in back garden) and unlike my local CP branch, they were more than happy that I wanted to give her a safe and loving home.
So hang in there; when it's right you'll meet the right kitty or kitties, and it will feel right to give them the loving home they deserve!