What it seems that is happening to you now is you're reflecting on past decisions and choices. This is a wonderful thing!
Right now, Mercury is in retrograde. It is not a great time for starting new things nor to make radical changes in our lives. Instead, it is a time to reflect on where we are and where we want to go. This is a cycle that occurs every 88 days.
To reflect in a productive way takes courage because you must do it with complete honesty with yourself. And be mindful to be compassionate with yourself as well.
You need to learn how to meld the two different personalities that exist within you. This will bring you balance. It will not happen overnight. It's a journey.
Make the best of it by tapping into that light hearted Gemini that STILL very much exists inside of you. Use this invaluable aspect of yourself to take yourself through these times that are feeling dark for you. Make a game of the reflection period. Play with it. No one plays better than a Gemini!
Our sun signs are not all there is to us. They are a good assesment to our likes, dislikes and what makes us tick. But they in no way decide our fate or choose our paths, so to speak.
Numerology is a great source for insight as to where we are, and where we need to go. Explore that! Its a lot of fun!
Find yourself a place that you can relax and be comfortable with yourself. Be it outdoors or indoors, whatever makes you feel the best.
Think back to what prompted you to decide to take this desk job. Ask yourself what made you feel it was best for you at that time. Once you have that answer, ask yourself why. Explore as many aspects as you can.
Do the same with why you left your previous job. Make a list of these things. Take your time in doing these things. When you have the lists compiled, you will have a good indication of what kind of job would be satisfying to you. Once you have that, you can start embarking on the road that will take you to it.
Again...make this fun! Make it a game for yourself. Otherwise, your Gemini nature can get bored, and you could easily begin to manipulate yourself into believing this is no longer an issue you need to address.
In the meantime, as you cannot walk out on your job right now, try to find something outside of work to compensate what you are lacking in your life that is preventing you from feeling happiness and joy. Whatever is lacking, compensate for it as much as possible outside of your work day. It'll help bring you back to a more balanced state. That is what I sense your feeling of depression is.
You are probably lacking in something stimulating on an intellectual level. Find something that stimulates you. Force yourself if you have to in order to get started. Whether it's light hearted chatting to an acquaintance or a crossword puzzle, whatever. Whatever is going to work for you will be something that you enjoyed in the past.
In darkness..we will always find our brightest light!