Also comming in late and make an alaytical contribution
But firstly well done for asking for advice. Willingness to learn is the first requirement to become better. There is a list of good advice above.
From your description it sounds like you should work on your confidence as a referee. Lack of confidence is extremely common in new and younger referees and unfortunately some coaches use this to their own advantage.
There is no easy solution to become confidant. It comes with experience. One good tip I received was to pretend you are confident untill you actually are.
Sell every decision you makes as though you are 100% sure of it. When you give a free kick a nice loud whistle. Every hand restart signal like throw in should be sharp with straight arm and standing up straight giving the body language signal of surity. If there is an appeal and you think there is no foul, a quick loud NO. This should all give the appearance that you are confident (not arrogant) and you are not going to put up with people trying to change your mind.
Lastly once you have restarted the games after a decision, get it out of your mind and put it behind you or it will lead to mistakes.
Enjoy you refereeing.