My chances of getting into UC's

I got 1320 on my Sat, but I got a really low score on my essay. I retook the Sat, I got higher score on the essay, but I got lower score on the Sat overall. And my major is chemical engineering, should I be worry?

Your Math and EBRW score is more important than the essay portion of the SAT. The UC’s will take the highest total score from a single sitting. Depending upon which UC’s you applied, your 1320 could be competitive or not. Just remember that the SAT is only one part of your UC application so GPA, HS course rigor, EC’s and essays all can contribute to your acceptances and rejections.

Here are the 25th - 75th percentiles for SAT (Math+EBRW) for all campuses based on 2017 data:
UCB: 1280-1490

UCLA: 1280-1500
UCSD: 1250-1470
UCSB: 1210- 1450
UCD: 1190-1430
UCI: 1190-1420
UCSC: 1170-1380
UCR: 1090-1310
UCM: 1020-1230

Here is my Stat
My UC GPA is 4.08
I took 4 AP classes total
I did over hundred hours of vonlunteer work
But I also got 2 C’s my Junior Year
I applied to UCI, UCSB, UCD, and UCSD as my high reach
I came from a small town, first generation to go to school
I’m in band and also in track and cross country at my school

Thanks so much for helping me out

You have a solid UC GPA and your SAT test scores are within range for all the UC’s but I would say that UCI and UCD are your best chances but not solid Match schools. UCSB will be tougher due to a smaller Engineering department and their Chem E program being highly competitive. UCSD will be a Reach school. Hopefully you have some solid Match and Safety schools on your list and Best of luck.

Honestly, you are a coin-toss for UCD and UCI, I hope at least one comes up heads.

you are a better match for UCSC, UCR or any CSU other than CP SLO.
Hopefully you applied more broadly.
Good luck