Air Girl
Without seeming patronising, I have seen this kind of under confidence many times, usually from those who end up the safest and best pilots.
You seem to be taking all the right steps, but you are involved in an activity which for you is novel and slightly scary.
My advice, FWIW, is don't even think of quitting, and be guided by your instructor as to when you are ready for solo. He or she has been trained to know the right time and circumstances.
I would be surprised if you don't find yourself quite relaxed when you actually do it, and afterwards get the surge of self confidence you need. I have spent many hours in debriefs asking students not to beat themselves up for minor mistakes. Hell! I'm still making the odd one after 10000 hours as instructor/examiner on pistons and jets, and learning from every one.
Level 400