Sometimes I feel the way you do: running in circles, spinning my wheels, and dissatisfied with my accomplishments. You are putting in long hours on the job but you are not happy with your progress. Moreover, you're worried about what your boss thinks.
I sense you have a good relationship with your supervisor, yet he/she has not given you enough feedback it seems. This omission could be due to a heavy schedule, and/or your boss is pleased but hasn't said so, or management is planning to let you go.
Here is my suggestion:
*Write a brief note to your boss and request a 10 minute meeting. State that you would like to know how to better meet your job requirements and surpass them. Go to the meeting with a smile, a handshake, and a notepad. Then put the feedback to work for you.
Let me know your progress.
Dr. Joan's Harmony Key: Shake the hand that pays you.