First, I am very impressed by how much you have a accomplished so far. As stated above in a previous response not many people get in a brisk walk and 5 miles per day.
The question you need to ask yourself is do you feel you are reaching your personal fitness goal based on the amount of exercise you are getting on a daily basis? If yes, you are getting in the right amount that you need to reach the desired goal. If you feel you are not making progress towards your goal, you may want to consider reevaluating your goal and what you need to do to get there.
Best of luck to you! Feel free to reach out to me with any other questions.