Also, in some cultures (Eastern Europe, I assume; Romania for sure) it's considered appropriate to gift an odd number of flowers (I never knew if it was about the actual flowers or how many stems?), as even numbers are associated with death and funerals, as you've mentioned.
One flourist (russian one) told me that even number of flowers are for funerals, because the word "чётный" - even number - has the same root as "сочтены" (дни) - days are counted.
> So maybe be careful with a new Chinese girlfriend.
It's worth noting that on 七夕 popup flower stalls appear everywhere. Flowers are an expected gift to your Chinese girlfriend. You should give her 11 of them.