I hope that you are experiencing marked improvement in your voice. You should be doing so if you are a diligent student. I found these useful breathing exercises in a book by K Behnke and found them useful. There are much simpler exercises, but we will talk about them later:
EXERCISE 1
Breathe in slowly, steadily and quietly through the nose
Hold the breath for TWO counts. While holding the breath, open the mouth widely and let the air escape quickly and quietly.
Don’t breathe for TWO counts.
Repeat the exercise three times.
Rest for 30 seconds after the fourth repetition.
Repeat the entire exercise three more times taking 30 second rests after each set.
EXERCISE 2
Breathe in slowly, steadily and quietly through the nose
Hold the breath for TWO counts
Release the breath suddenly while saying HAH
Don’t breathe for TWO counts.
Repeat the exercise three times, breathing out on HAY then HEE.
Rest 30 seconds after the fourth repetition
Exercises 3 and 4 will be done next time. It may be a wise idea not to do all these exercises in one sitting. Actually, I must confess that I myself have never really gotten beyond exercise one except on a few occasions. It is quite good. Enjoy
Reference
Behnke K (1948) Singer’s difficulties – how to overcome them Britain: Lowe and Brydone Printers Limited