The other recommendations were sent online through the common app portal correct? Are you sending these in yourself? So that you don’t have regrets either way - can you all admissions tomorrow (or a parent if you are in school) or right after school, etc., and see what they say? Did you send the initial email to YOUR admissions advisor? Every school is assigned one. Most of their entire job is replying to students! Explain the situation, kindly ask if it would be ok to send in an additional rec given you were a high school transfer and teachers may not know you as well.
http://www.usc.edu/admission/undergraduate/findyourcounselor.html
But…the recommenders (teachers) many many students use don’t know them till junior year. I think that applies to most at a high school of good size. And some GCs hardly know they kids they write for and do it by a survey, so I am not sure you are at as big a disadvantage as you think.