18M NEED SOME ADVICE

i 18m and i am in first year btech and today out of blue our professor picked me to talk infront of my whole class and let me tell you i fuked up real bad when i was small i used to give public speech to as much as 1000+ people and now i cant even stand in front of 50 people

the most main reasons behind my low confidence is my height i am 5`2 and weight 35kg

i am very much confident with my friends but i always fumble in public speakings due to low confidence