I've been having white discharge that smell like onion from the cervix (no itch) and vulva coloured purplelish and abdominal pain. std or pregnant?

Pregnancy test?: you should be able to take a pregnancy test pretty easily. If negative, you may want to see MD. STD possible, or yeast infection, or normal

Hard to guess: It can be hard to tell if a woman is pregnant because some of the symptoms seen in non-pregnant women also happen in pregnant women. A home urine pregnancy test gives a reliable result if done correctly. One can test about 3 weeks after sex (3 weeks after when conception might have occurred), or 1 week after missing a period. An Ob-Gyn doctor can evaluate any persistent or worrisome symptoms.