That's right. It might be a theoretical model. It might be an empirical model, though. You are limited to estimating no more than three parameters. For example, I should how to profile the response using a linear regression with three parameters, one for each factor, but omitting a constant term (intercept). This example is an empirical model.
There might be additional effects of any of these factor such as interaction effects and non-linear effects, but three observations are insufficient to model or explore such effects.
You might consider using a designed experiment to collect the data for estimating the desired parameters and include extra runs for error degrees of freedom. You could start with the three runs that you have in hand and augment them in an optimal way. My suggestion assumes that you can control factor levels. That is to say, your data is not an observational study.
As to how to follow my suggestions, please see the JMP Help for fitting linear models, in general, and launching the Fit Least Squares platform, in particular, if you want to replicate my result.