Your level of confidence should always be a little below your level of skill.
Overconfidence kills pilots and their passengers.
Your lack of confidence is not only normal, but also a sound reaction to your low experience.
I had to fly almost a hundred hours before I felt confident enough to take non-pilot passengers, and to have passed my CPL to take my children with me.
Flying with an instructor at a school is certainly a good idea, but you will only do again what you did before.
When I finished my PPL, I did my first flights with a free lance instructor, we travelled here and there, doing real flights, and not pre PPL skill test flights.
I do the same with my IR as I don't feel confident enough after the skill test to travel in real IFR.