WHO SAID that you need to reposition? Have they seen or heard you play? Are they monitoring your progress. Whether or not you NEED to do anything (except practice more - we all need that) cannot be read in an internet forum - or anywhere else. Changing habits only works when you know WHAT is wrong, WHY it is wrong, WHAT is better and WHY it is better. Do not frustrate yourself with DIY embouchure. Believe me, it is just not worth it! Get professional help, it's worth it!