Look the paper that I sent to you. In this way, the authors applied an interesting method which they classified as the "gold standard" . In addition, I sent to you another material that I believe it will can help you.
I hope this helps.
Article A general approach for sample size calculation for the three...
I am not 100% sure if this tool would be useful for you but in psychology (social sciences) I used GPower analysis and this application is available for free online (unless some 'dramatic' change occurred recently).
What do you mean uneven examples, please clarify. Also if you would like to maximise power you would need to increase your sample size and then you may detect effects otherwise not seen in underpowered research.