I never suffered from imposter system. If anything I have the attitude that I have more qualifications and work better than lots of people. When I was younger I was surprised that other peers from college were getting good jobs and I was not getting chosen for these jobs. If anything, I have a superiority complex. Outside of work, I am quiet, don't make friends easily and am embarrassed to be the centre of attention. If I am explaining a work issue, I just want to get it sorted and don't care about being the centre of attention.
I am from a working class background, really struggled to get my first job after college even though my grades were near top while peers had contacts, parents owned companies etc.
I rose up very slowly, so I was more than ready for the next stage of work by the time I got it. Also it involved a lot of using initiative, not being afraid of complicated tasks, in general developing skills which are scarce in my industry. I did not have contacts/nepotism to get me a job.
Don't be afraid of not knowing things. I don't know a lot of the queries but I ask people, read up on information, and make my decision. Things are changing so fast you won't ever know all about a job. However you should be confident of sourcing information and applying it. If you don't know after doing the research that is fine too. Take regular hols from work, even if you are not going away. I take a week every 10 or 11 weeks. It keeps the brain fresh. Relax, regular exercise etc, do not work long hours. Try to unwind when not at work. Your ability to think and analyse are impaired by overwork. Act confident, walk tall. Watch what other people are wearing and try to wear similar. It will give confidence if you fit in with clothes.