US Citizenship of baby born in the UK

I have a question about: Evidence of parent(s)'s identity and U.S citizenship part of applying for my little ones (to be she's due in July) social security and passport from the London US embassy.

 I have my old passport but it was only issued in the US two months before I moved to the UK. Would this be enough evidence to show that I has in the UK previously for 18 years before that point or should I be thinking about getting old high school transcripts?

I was always confused when they would ask for stuff like transcripts online because they don't actually ask for anything like that in the Embassy.  Did you grow up in the US? At my interviews for little ones, they asked me things like where I grew up, schools I went to, streets I lived on, high school mascots, etc to gauge my response. I had no trouble showing I had grown up in the States, and they didn't need any more. If you have things already that demonstrate that you were from the US, might not hurt to have them, but don't stress too much.

Thanks, yes I grew up in the States then went to university over here (before working, marrying and now awaiting my British citizenship application to be approved via mail). Friend suggested we go shortly after the birth of our daughter to get her SSN and passport in London but was thrown off a bit by the evidence of my US residency.  All my old documents are mainly showing my UK residency in 2002 onwards.

Read this:

http://travel.state.gov/law/family_issues/birth/birth_593.html

noting registering the birth after your baby is born.

and this:

http://travel.state.gov/law/citizenship/citizenship_5199.html which says:

Birth Abroad to One Citizen and One Alien Parent in Wedlock

A child born abroad to one U.S. citizen parent and one alien parent acquires U.S. citizenship at birth under Section 301(g) of the INA provided the U.S. citizen parent was physically present in the United States or one of its outlying possessions for the time period required by the law applicable at the time of the child's birth. (For birth on or after November 14, 1986, a period of five years physical presence, two after the age of fourteen, is required. For birth between December 24, 1952 and November 13, 1986, a period of ten years, five after the age of fourteen, is required for physical presence in the United States or one of its outlying possessions to transmit U.S. citizenship to the child.) The U.S. citizen parent must be genetically related to the child to transmit U.S. citizenship

luckily my high school offered to send me my high school transcripts this week. So that should be enough.