My contacts are BC 8.5 and DIA 14.2. Should I go with an 8.4 or 8.6? and is 13.8 DIA ok if the only option?

Looking at ordering the Night & Day contacts. Does it make a difference going up or down slightly with the DIA? Obviosuly I have to go one way or the other, just would like to know which is better. Also, the only DIA they come in is 13.8 but my prescription is 14.2. Will this make a big difference? Thanks for any input. I have tried to research but not much luck.