Hi Sunshine,
I've a 6.5 & 2 yo and yes, I think your little one will come to that point when she realises that she is 'minority', it will be but a phase which she will outgrow... how well she does that might depend very much on how you help her with it.
Coming from another mummy's tummy does make her different but also unique. Depending on your child's personality, she might even like the difference. This noted difference is another disclosure opportunity for you. Take this chance to talk about adoption and how happy it has made your family, for eg, and how life without her would be.
Being part of a support group is good though the reality is majority of friends around us are biological families and embracing it will help your girl sail through this.
When my girl was 5, she reacted in 2 ways: she cried when she asked me why her classmates' mom can have so many babies unlike me and on another occasion, she said she preferred not to tell others she has 2 mummies and daddies because 'how would they feel, mom, they only have 1 each!'. Like as if I was the insensitive one! Which was very funny.
All the best,
Andrea
