During the work time today, I was lucky to have Mr. Lyons sit with me to discuss my data. Similarly to my initial findings, plotting out the full data set showed that galaxy size does not affect brightness. That is,bigger galaxies are not necessarily brighter.
There was, however, an unexpected result. We found that, on average, the galaxy brightness tends to correlate around luminosity 10, regardless of the galaxy size. I'll be looking forward to discuss this result with Professor York tomorrow. Hopefully, we'll be able to come up with an explanation.