From your post you think you should (?) not feel this way - as you said, you have family, friends, work. And yet something is missing.
Beyond blue has a site specifically for Covid related issues that might be of use to you...
One thing I know from speaking with some people is that with Covid and the lock downs, there is a greater sense of disconnection or perhaps better said as a loss of connection and increase in loneliness. And if you are working from home this feeling may be amplified. Where once upon a time you would be able to visit someone, travel etc., Covid has put a stop to these activities. My heart goes out to you ... someone outside of our control is controlling what we can or cannot do.
Other users in the forums have expressed similar issues to yours, and in one example, both persons were living in the same city. I was listening to a podcast this morning and the host of the show is also a therapist who said she has been feeling down more recently, and the last 2 years have been the hardest.
We are all affected in different ways and not know where the end point is I think is very frustrating. So in this mess, I am not sure how to find clarity except to do the best we can and look forward with hope? And maybe telling your story here will help?