Don't be discouraged, we all had to start somewhere, you are doing better than you think you are.
Your insight that you could improve is actually the sign of a true professional, he or she always try's to improve on every flight. I always go over, in my mind what I could have done better and try to apply it on my next flight.
On the other hand, as already pointed out, don't obsess or worry needlessly about mistakes, or a less than perfect performance, no one else is.
It is a constant learning situation and process of self improvement, from the most inexperienced new Pilot to the experienced veteran, at least it should be.
Incidentally, even after having flown jet transports for many years when converting onto a new type I find it takes me about a year to be completely comfortable with it, there are lots of nuances and things to learn, especially when changing to a different manufacturer.
Work at it, but most of all enjoy
