I have an almost daily painless but thick and gummy vaginal discharge about the size of a pea which is white/ yellow. should i be worried?is this std?

Yes, possible STD: Any new or unexplained vaginal discharge should be professionally examined, and colored vaginal discharge (yellow, creamy, etc) and mucus ("gummy") suggest an infection, perhaps involving the cervix. STDs (gonorrhea, chlamydia) are among the most common causes, especially in sexually active persons your age. See a doctor or clinic this week for sure. Good luck!