19F NMR line spectra
I think you have got the calculation right. However, I would also consider the coupling between F and H because coupling through 3 bonds is also usually visible. So, each of your 8 lines will be split into four by the H-atoms.
That will be the major part of the spectrum. You would also get weak signals with a different splitting pattern due to the other isotope of boron ($\ce{^10B, I=3}$, abundance=20%).