I was in a position similar to yours last year. I got a 28 on my MCAT after not studying much and interviewed at my state school. I knew that my score wasn't great, but didn't want to retake the MCAT if it wasn't necessary. I found out that I was at the bottom of the waitlist at the end of March and was very upset, but spent the summer studying for the Aug. MCAT and got my score up 5 points! I was much more determined the second time around.
This year, I have been accepted at my state school and everything has worked out for the best. I really don't think taking the Aug MCAT hurt me in the admissions process. If you get in this year, congratulations! If not, don't worry about it at all. Spending more time studying definitely will improve your score and you will get in next time. You can keep working with disabled kids, which will show that you are determined to enter medicine. But if I were you, I wouldn't waste my time studying for the April MCAT if it isn't absolutely necessary. Good luck!