It’s about more than just producing a certain sound.
It is also about the fact that your voice connected to who you are, and how you feel about yourself. This is integrated into your voice feminization training.
Set goals for yourself and evaluate your voice as it is right now. Try to figure out what those little things are that would make you sound better to yourself. This is creating the baseline to start with voice therapy.
Your voice is not a separate instrument, it is intensely linked to how you are doing and what you are feeling. Not every day is the right day to practice your voice exercises. Be mindful of how you are doing, and take care of yourself first!