How to ask my professor to write recommendation letter for me?
Your e-mail looks okay as an appointment mail. There are a few possibilities. The professor may be busy with some important things he has to do. He may be on vacation, not available. Please don't lose your confidence yet. You probably should wait a few more days for him to reply. 

It is also possible that he didn't think an A in Calculus I is good enough for him to write a recommendation letter for you. He may want to wait until you get another A for Calculus II and then write a good recommendation letter.

However, depending on which field you are going to study in graduate school, the professor who taught you Calculus I may not be a good candidate to write you recommendation letters.

You already have Bachelors degree. I think the recommendation letters written by the professors in the university where you graduated from, who had more working experience with you would be more helpful for your graduate school application.