Hi Jan
You may want to hear more from graduates than form educators however I'll give you my impression.
When going into a new area of practice it is normal to feel inadequate and this gets better the more you rotate through new areas over your first few years.
However with the delay in employment in your country and that we now are having similar problems with the job tightening a delay in taking up practice must surely exacerbate the situation and your feelings of inadequacy. I am sure this is not an ideal situation.
However I would advise you to front up to the feeling. It is good in a way that you do feel that way because at least that way you aren't "fooling yourself" about competence. "Known incompetence" is a way stronger position to be in than "unknown incompetence" even though it is uncomfortable.
Having a plan of how to improve your knowledge and skills in a practical way can help. For example it may be a case of making sure you have a really are systematically working through your theory from your course textbook and literature in the area of older adults and Neurorehab and applying it as your patients turn up; putting the work into reflecting on how to better assess and manage patients, clinically reason etc.
How do you find your supervisor(s)? Are you able to discuss this with them? Getting good support in your first job is very important in building up confidence and sometimes being forthright and open with them about your perceived difficulties can be beneficial for all. Rather than seeing you as less adequate a good supervisor may perceive you as reliable if a bit cautious and be able to know ones limits and ask for help. And you may feel less intimidated.
Another strategy that can help is joining your special interest group in gerontology/neurology. You might attract a mentor or two by doing this as well as finding other people in the same situation as you.
The question is how can you move from a position from this position of lacking confidence and competence to being the very best physio you can be in this area of practice? Remember your undergraduate course was only just a beginning. The work has really just started!