기다리다 Present and Past Tense

Hello there,

Why does 기다리다 become 기다려ㅛ instead of 기다리아ㅛ for present tense and vice versa with the past tense. From my understanding if the verb stem ends with ㅏ or ㅗ its form is 아ㅛ for present tense and 아써요 for future tense (not sure if i typed the future right). So why does it become 려 instead of 라