Hi, these are common problems in everyone's professional career when you move up the ladder into managerial position. It's important to understand your strengths and weaknesses first and take steps to address those weakness. In fact you organizations should help you to handle such transition.  Be confident that it's not a problem and you can overcome this with little guidance.

Do a self assessment to analyse the strengths and limitations within you. When you are instructing your subordinates,  remember your position as a manager and not as a person. A manager's job role is to get work done through her team members. Work on developing your delegating skills by focusing on the process. Talk to be assertively and confidently than masking yourself with personal nature. Consult a Counselling Psychologist who can help you with life skills.

Hello dear these are your personality traits that are stopping you from behaving in such manner. Try consulting a mental health professional such as psychologist either through online consultation or meet in person to analyse you better and then suggest the changes that you can make and how.