You sound a little out of your depth.
Is this a role that you are qualified in (or part qualified)? If so is this the first time your are putting academic qualifications into real scenarios? I noticed you talk about projects, so are you Prince or Agile qualified? I have found that these methods are great for generating paper trails and for delivering tangible things like a new IT system but in reality people label things projects when really their not - they just want to get something done.
I assume from what you’ve said your manager also has a role in delivery and the “management of people/person” is an add on, so whilst you are frustrated perhaps he/she is up against a deadline too?
Rather than say “what should I do”, perhaps it’s more effective to say “someone has approached me about xyz. I’ve checked back on some records for a similar project and am thinking of doing abc, do you think I’m on the right track?”.
In the example you gave about someone contacting you for an update on something you haven’t been involved in, couldn’t you contact the person who did deal with them, and ask them for an update - or again look for a file and see what you can find?
I find in most cases you don’t need to know everything, you need to know the person(s) who knows that particular thing - especially as you are bedding in?
When they employed you, did they know they were getting a newly qualified employee, with less hands on experience? When you have a cup of tea/chat perhaps it’s worth mentioning that “on paper” and in reality are quite different.
Ask your manager if you can join him in meetings as an observer to learn about the environment your operating in. Others who are in similar roles to you - ask if you could shadow them for a few hours.
You might think your manager is being difficult but it could also be that he feels he’s answered questions before. It could also be that he feels (rightly or wrongly) that the time he’s spent “managing” you is time last on his day job, and he’s struggling to make up that time.
Managers are constantly being told to adapt their style for the individual’s they manage (and the good ones do) but that works both ways and perhaps you need to adapt a little too.
How long have you been in the role? I think it takes a good six months to feel settled.