You could try plotting the standardized residuals and see if very few of them have an absolute value greater than 3.
But the elephant in the room is, if perOOgivenP is a proportion, you need to normalize your data (at which point even more of it will become missing observations). Ideally, you would have a large enough number of trials for each observation that the zeros would be replaced by small real numbers. If that's not practical, perhaps you could try Poisson regression or survival analysis with recurring events (you can use Subject as a clustering or frailty term).
But in any case, the data as shown violate normality assumptions.