I have been using Pink Pad for years now and it has been great!! It has helped me so much in keeping track of things and when to expect cycles. One of the best parts is if you create an account it can save all your data and transfer it if you need to. In my case I go a new phone and did not want to manually go in and put the past couple of months myself, so the app did it for me just by me logging in.
Vren91 about Pink Pad, v7.1.0