I guess you mean the midwestern American accent. Central America means the countries lying between Mexico and Colombia. I'm curious what you mean by "in my mind"... have you recorded yourself speaking and listened to how you sound? (Traumatic, I know.) This would be useful in defining exactly what you need to do. It seems that you're getting enough input, so focus on the output.

I definitely agree with Peachey here. Recording yourself would be very helpful. One thing I might suggest is that your input sources all seem to be textbook sources. These can be very helpful in breaking down how to pronounce consonants and vowels, understanding word stress, and teaching proper intonation and rhythm, but it might be helpful to also use authentic sources. A good source for a Midwestern-type accent is news broadcasts. Studying them may be great application for the courses you have been taking. In one comment you said that you have already moved to the U.S. In looking for feedback, you can always ask your friends to help. For instance, if you're trying to change the way you say 't,' then you can ask your friends to tell you every time you say your 't's in an Indian way. I hope you find these helpful. Best of luck!

allready moved :-)

move there