It matters not whether you are an artist or a photographer, working out your thoughts is part of an ongoing process that helps you understand what you are doing or trying to do. Sometimes/often people cannot work this until after the event. It needs distance. You can try and work out what you are attempting for each project - in a goal-based way, but my feeling is that you never really know what you were doing until you achieve the critical distance that comes with time, with looking back at a group of work at quite a later date.
Often it needs the impetus of trying to explain things to another party to get it down – even if that party is imaginary – but it helps to look at your work through another's eyes, or just over their shoulder.
But what you write for your own understanding and what your are trying to write about the work for other people, may be two different things. I suggest not to tell people what the work is about or what it means, unless it is in a round-about way. Tell them what led to the making of the work, what you were interested in generally what inspired you, but then let them make up there own minds what it means, if anything. So write what you think it is and then perhaps write another version for potential viewers that frames their way of looking and leads to questions.
Of course if you are a dab hand at taking photos and know how to lead the viewer in by some preternatural instinct, maybe you just don't need to do this at all, because you already know what you are doing and the viewer can already sense that.
Some people don't talk about the work at all, they simply talk about life and everything else – and somehow that is enough to draw people in.