Hi! "du gebärst" is the preterite subjunctive (conjunctive) mood form of "gebären" and is not in use at all. The 2nd person singular present tense indicative mood active voice of "gebären" is "du gebierst". The 3rd person is "er gebiert" and "du gebärest" is the subjunctive mood of the 2nd person. But the most common form is the participle "geboren". That is why most Germans have difficulties in conjugating this verb.
I'm writing it in here since the question has already been "resolved".