lack of confidence solo flight

Very normal and typical experience you're having. I've only recently
become confident and more comfortable in my abilities. I've only got
about 130 hours, but I made a lot of effort to build my confidence by
flying lots of cross countries, taking an aerobatics course, dealing
with complex airspace, night flying, and flying in less than perfect wx
days.

Like Dudley said, I still feel an "edge" starting from when I get close
to the airport on the drive down until I start the engine. It helps me
concentrate on what needs to be done and makes me take things
seriously. But I'm also far more relaxed and at ease now than I was
even a couple of months ago.

The worst thing you can do is after your checkride is once a month
flyiing or just sticking around the local practice area. The more
experience you get, the more comfortable you will be.