As you have US citizenship, just begin to look for jobs and see, what you can find? Talk to your relatives, look at US forums, and in case you have no other commitments, just move there and try.
Concerning engineering: The problem is, engineering is a word which is in some languages used for everything from a bicycle mechanic to someone calculating plasma movements in fusion reactors. And also in the UK BTECS are from what I see on the highest level comparable to an apprenticeship, which is simply not the same as a university degree. Nevertheless, it can lead to exciting job opportunities depending on the field and the industry. But depending on the country your in, your career will have to stop at one point (unless you educate yourself further) on the technical side. An BTEC simply educates you for another type of job, than a university degree in engineering.
Generally smaller companies are more open to non-classical educational profiles, than the companies, who have automatic presorting computer programs.