Unbalanced within-subjects design

Hi everybody,

I’m currently setting up a model to analyze experiemental data. The design is a simple 2x2 within-subjects comparison with N=20 subjects (factor 1: first testing vs. second testing; factor two: on vs. off medication). However, the number of participants in the experimental cells is not balanced (i.e., 8 subjects first off medication and second on medication, as well as 12 subjects tested first on and second off medication). I now want to do a linear regression on my dependent variable (y = group_mean + testing + medication + testing*medication + individual_mean).

Do you think that I run into trouble with the interpretation of the fitted variables, as, for example, more people in the first testing were on medication than off medication?

Thank you in advance!