Congrats on finishing (did you take the sample?). For predicting your score, the exam is highly variable and can theoretically look like any of the FLs you have tested or none at all; beyond simple things like amino acids, psychology stages, cells, simple equations, etc. that come up as part of every exam, the remaining majority of each exam has different topics. For that reason you can't just use a single exam to try and predict your score. If you would want to do that, in theory, FL3/4 are the most recent exams put out so should be most 'similar to the real exam at least in style; but your scores are quite different and more similar to your first two.
Based on your scores, your FL average is 518.5 and you can reasonably expect to score +/- 3 of that score if you took your FLs in real testing conditions and have a similar experience on test day.