I don't think you can help whether you do/do not hurt your parents, that is based on their attitudes, thoughts and feelings. I would just do your best to live your life as you want and start putting up "simple" boundaries, especially when talking on the phone, saying things like, "I am not going to answer that, Mom" and then changing the subject. Try to get your mother used to you calling her rather than she you by starting a conversation you initiate with information/news, whatever you want to share on your terms. If she calls though and starts the 3rd degree, make an excuse for why you have to get off the phone (set a timer to go off and when it rings tell her your dinner's ready or you are going out to meet a friend and don't want to be late, etc.) and then give her a breezy, "I'll talk to you later! Bye!" and hang up.

Your father may/may not be disapproving of you; he may just be trying to live his life "over" through you, do things differently he wishes he'd done in his life, etc. Tell him you are happy with your life, enjoying your job, etc. and he will look "silly" if he argues with you? If someone says they're happy, you have to agree, you can't tell them how they feel? Be aware of and stay close to how you feel and in places you are not sure, come up with pat statements/answers such as "I have to figure that out for myself" and just keep repeating that/whatever, like a wall against opinions you haven't asked for/don't want.