I absolutely love your question. Why? Because I was where you were. I questioned everything. Not because I didn't know but because nursing can be tricky like that. Things that seem straight forward can change on you.
I learned that asking questions is a good thing. It shows you care and that your mind is always working. Don't worry. Even the best nurses, the ones who seem the most competent can be functioning on autopilot. And you might have a question they don't know the answer to. We don't know everything. No one does.
You'll learn who to ask. You'll gain tons of experience and you'll learn how to answer difficult questions. I have a hunch that you'll be a great preceptor one day and make the new grads feel at home. There's always someone who likes to make others feel foolish for asking a seemingly obvious question.
You will overcome the second guessing. Here's a tip. Do case studies in your extra time. The ones with rationales. Your critical thinking will grow. And if you can remember, if you have the time, write down the questions you had during your shift and walk through them again later.
Don't compare yourself to others. Things aren't always as they seem. You will do fine. The reason why they might say you ask too many questions is that nursing is busy and you might possibly be slowing them down.
Be patient with yourself. You will do great! Good luck and God bless! And CONGRATS on your new role.