This app was mentioned in 2 comments, with an average of 3.00 upvotes
For android I use Insulator: https://play.google.com/store/apps/details?id=com.bendywalker.insulator
It's the best balance between ease of use, nice looking interface, and usefulness.
There are more simple ones, and more detailed ones, but this suits me on MDI.
Congratulations! I also made an insulin calculator a couple of years ago to ease myself into Android development. I still work it on it here and there when I find the time. I'm currently working on version 4 ��