Must a girl abandon the medical profession she desires in order to wear the niqab, especially since she swore to wear it out of anger, in response to suitors, knowing that the niqab may conflict with practicing medicine in her country?

The preponderant view among the jurists is that covering the face is obligatory. Therefore, you should strive to search for a university where you can study medicine while covering your face. If you find a way to do so, then praise be to Allah, for religion is too precious to be sacrificed for worldly gains. And whoever fears Allah, He will make his matter easy for him. And whoever gives up something for the sake of Allah, Allah will compensate him with something better.