Very early on, I believe during my first u/s the RE mentioned the gestational sac was measuring large.
I naturally googled it and googled it and googled it. Please do not do as I did- it just caused unnecessary worry.
I asked the next few times I saw the RE and nothing ever came of it.
I am just getting back from a beautiful walk with my 3 month old, from that very pregnancy. All ended quite well.
So good luck. It doesn't hurt to hold off at week 6 announcing any pg, maybe that was what he was getting at?
As for the nausea, I used acupuncture 'tacks' (the short pins) in my wrist pulse points (where the sea bands go) and I also was on benedryl for seasonal allergies. Both my RE said were great for curtailing nausea.
GL and let us know how it all goes.