Is the number of students in your class at least 17 (i.e. so that your #1 rank is top 6% or better)?
Have you and your parents used the net price calculator on each college on your list to see if it is likely to be affordable?
UCLA does not offer need-based financial aid to non-California residents. Therefore, it is a high reach for the Regents’ scholarship (“If a Regents Scholar has additional financial needs beyond the $2,000, the scholar will be awarded a university scholarship and/or grants to cover the remainder of the scholar’s need.”) – i.e. significantly more difficult to get than admission (which is likely a reach anyway, more so for any engineering major).
Williams and Harvard do not have chemical engineering.