@vintage lover, just my opinion of course but if it were me and I could afford it, I'd definitely upgrade to the 8.5-9.5mm pearls. It seems the white, round 7-8mm (or thereabouts) strand is the first one everyone typically gets- then soon no longer wears.
But I don't think I've ever heard anyone say they regret their 8-9 or 9-10mm (or thereabouts) strand because it is too large on them, once they wear them for any time at all. Those are not huge pearls at all, even though they may seem large (for a very short time only, in my opinion) when you are not used to wearing pearls. But if you're like most, you'll never be sorry you got the larger pearls and they won't end up forgotten at the back of the jewelry box, either.
Either way, please let us know what you do and best wishes!