Econ major (and also a one-year transfer) chiming in:
Economics (especially at UCSB) tends to base their admissions more on GPA from applicable courses rather than overall GPA so it’s reasonable to deduce that your Chem grade won’t weigh too much.
Since your review will primarily be based on your grades from (what sounds like) only 6 or 7 total classes, I recommend completing as many of the major prereqs and related courses (Micro, Macro, Stats, and Calc II for UCSB with Calc III and Linear Algebra additionally factoring for UCD) in the Fall and Winter to help establish your economics potential.
It’s also important to note that since the adcoms factor APs as mere units for transfer admissions, any 4’s and 5’s won’t necessarily boost your admissions profile more-so than 3’s. If your using AP credit for any of those aforementioned classes, I would even consider “retaking” their CC equivalents for a letter grade to further prove your aptitude for the major.
IMHO, since you don’t qualify for TAG, it’s going to boil down to if you can convince the adcoms of your current academic ability (through your Summer, Fall, and possibly Winter grades) otherwise it’s very easy for them to rationalize that other applicants simply have shown more.