Which SDLC model to use?

Hello! We are currently having a hard time on which SDLC model to use for a medical app that provides diagnosis. Considering the limited time of the project, which is less than 5 or 6 months, training of the model, and the limited functionalities (e.g., no user registration), we are leaning more on using Agile. However, because of the complexity of providing accuracy in the field of medicine, waterfall and iterative are added to our choices. What are your thoughts on these? :>